This article was downloaded by: [National Taiwan University] On: 01 July 2015, At: 08:06 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Expert Review of Medical Devices Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ierd20
Interventional treatment of atrial fibrillation – contemporary methods and perspectives a
b
c
d
Bartosz Zuchowski , Krzysztof Kaczmarek , Lukasz Szumowski , Yi-Gang Li & Pawel Ptaszynski
b
a
Department of Cardiology-Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland b
Department of Electrocardiology, Medical University, Regional Sterling Heart Disease Center, Sterling 1/3 91–425 Lodz, Poland c
Department of Arrhythmias, National Institute of Cardiology, Warsaw, Poland
d
Department of Cardiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medine, 200092, Shanghai, China Published online: 29 Apr 2015.
To cite this article: Bartosz Zuchowski, Krzysztof Kaczmarek, Lukasz Szumowski, Yi-Gang Li & Pawel Ptaszynski (2014) Interventional treatment of atrial fibrillation – contemporary methods and perspectives, Expert Review of Medical Devices, 11:6, 595-603 To link to this article: http://dx.doi.org/10.1586/17434440.2014.941810
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Review
Interventional treatment of atrial fibrillation – contemporary methods and perspectives Downloaded by [National Taiwan University] at 08:06 01 July 2015
Expert Rev. Med. Devices 11(6), 595–603 (2014)
Bartosz Zuchowski1, Krzysztof Kaczmarek2, Lukasz Szumowski3, Yi-Gang Li4 and Pawel Ptaszynski*2 1 Department of Cardiology-Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland 2 Department of Electrocardiology, Medical University, Regional Sterling Heart Disease Center, Sterling 1/3 91–425 Lodz, Poland 3 Department of Arrhythmias, National Institute of Cardiology, Warsaw, Poland 4 Department of Cardiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medine, 200092, Shanghai, China *Address for correspondence: Tel.: +48 426 644 304 Fax: +48 426 644 269 [email protected]
informahealthcare.com
Atrial fibrillation (AF) is estimated to affect nearly 3 million people around the world. It is the most common arrhythmia and its incidence increases with age. Catheter ablation is an interventional procedure performed to reduce the patient’s AF burden when pharmacotherapy did not succeed in relieving the patient’s symptoms. The ablation is most effective in paroxysmal AF; however, many techniques are being developed to make this procedure more eligible for patients with persistent arrhythmia. The most common AF ablation technique involves separating electric activity of the pulmonary veins from the left atrium. Over recent years, many novel and promising techniques were developed (e.g., balloon cryoablation, circular catheter ablation, laser ablation, robotic navigation, etc.), which may further improve AF ablation efficacy. KEYWORDS: arrhythmia • atrial fibrillation • catheter ablation • cryoablation • interventional treatment • laser ablation • radiofrequency ablation
Atrial fibrillation (AF) is the most common sustained arrhythmia and a major cause of stroke. According to current estimates, nearly 3 million people suffer from AF. Its incidence increases with age, about 10% of patients aged 80 years or older suffer from AF [1,2]. Among its main risk factors are: hypertension, coronary artery disease, heart valves disorders, thyroid diseases, family AF history, alcohol and nicotine intake. AF significantly increases mortality (double in patients without anticoagulation treatment) and hospitalization rate while decreasing quality of life and exercise capacity. Its ‘natural’ course begins with short, rare, paroxysmal episodes of arrhythmia that gradually become more frequent and longer. Over time, the AF episodes become persistent and require hospitalization in order to perform cardioversion or administer intravenous drugs to interrupt the arrhythmia, finally leading to the permanent form where even cardioversion does not succeed in converting to sinus rhythm. Pharmacological treatment focuses on reducing the thromboembolic risk by oral anticoagulation and using antiarrhythmic drugs (AAD) to reduce AF recurrence and control the heart rate in permanent AF form. By the end of the 10.1586/17434440.2014.941810
20th century, new interventional methods of AF treatment were developed. History
In 1997, Haı¨ssaguerre performed the first percutaneous ablation of focal origin of AF [3]. In 1998, pulmonary veins (PV) were identified as the most important source of ectopic beats, which initiate paroxysmal AF [4]. Over the next few years, different ablation techniques were developed to electrically isolate PV from left atrium (LA) [5–12]. At the present time, we have advanced techniques of pulmonary vein isolation (PVI), which make the procedure more successful, quicker and simpler, while still following the same idea, that is, to eliminate electrical connections between the PV and LA, which allow PV potentials to enter the LA and trigger AF paroxysm. Contemporary techniques Radiofrequency ablation of electrophysiological breakthroughs
Principals of this technique were published by Haı¨ssaguerre et al. in 2000 [5]. It requires the use of a circular, multi-polar diagnostic catheter to map the PV for electrical connections called ‘breakthroughs’. This loop-shaped catheter is
Ó 2014 Informa UK Ltd
ISSN 1743-4440
595
Review
I
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
08
08.50
09
09.50
10
10.50
11
III V1 V4 HIS 1-2
CS 1-2 L 1-2
Downloaded by [National Taiwan University] at 08:06 01 July 2015
L 2-3 L 3-4 L 4-5 L 5-6 L 6-7 L 7-8 L 8-9 L 9-10 ABL 1-2
Figure 1. Pulmonary vein potentials recorded by poles L4–L8 of circular catheter in the ostium of left superior pulmonary vein during atrial fibrillation.
introduced into the LA through the transseptal approach (through either a patent foramen ovale or by a transseptal puncture) and positioned sequentially in the proximal part of every pulmonary vein to map them for pulmonary vein muscle potentials (PVPs) (FIGURES 1 & 2). The radiofrequency (RF) ablation catheter is also advanced through the transseptal route. The target for ablation is the muscular tissue at the pulmonary vein ostium where the earliest PVPs are recorded. Usually, there is more than one breakthrough and the subsequent ones tend to appear once the first one is ablated. The locating of breakthroughs is performed both during sinus rhythm and left atrial pacing (from catheter placed in distal coronary sinus region). The ablation must be performed as proximally as possible to prevent PV stenosis. In most cases, irrigated RF ablation catheters are used as they create wider and deeper lesions and reduce the risk of thrombus formation [13]. The end point of ablation in this technique is the elimination of PVP conduction to the atria. Circumferential RF ablation of pulmonary vein ostia
Circumferential PV isolation was developed by Pappone et al. in 2000 [6]. The technique involves the creation of a circular, continuous lesion around the PV ostia in order to isolate the PVs from the atrium. It implicates the use of 3D 596
electroanatomic navigation system (CARTOÒ3, Biosense Webster, Diamond Bar, CA, USA; EnSite Velocity, St. Jude Medical, St. Paul, MN, USA) to map the PV ostia and keep the ablation line continuous (FIGURES 3 & 4). The end point of the ablation in this approach is the creation of circumferential, continuous lines of conduction block around every PV. Contemporary, mixed RF approach
At the present time, RF circumferential PVI with the use of 3D mapping system is still widely used. However in addition, the multi-polar circular diagnostic catheter (commonly called ‘Lasso’) is used to check whether there are any breakthroughs present after PVI. If there are, focal RF ablation at the site of earliest pulmonary vein potential is applied. Usage of irrigated catheters is the standard. The PV may be isolated one by one or both ipsilateral at a time, for example, with the use of Double-Lasso technique [7]. Established end point in AF ablation is to achieve a bidirectional block between left-atrium and PV. The entry block (LAPV) is assessed by elimination or dissociation of pulmonary vein potentials on the circular mapping catheter located in the PV ostium during sinus rhythm and pacing from coronary sinus. The exit block (PV-LA) is evaluated by pacing from inside the Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
Review
pulmonary vein distal to the ablation line. If the pacing does not affect the atrial rhythm, the exit block is present. In fact, the unidirectional LA-PV block is very rare, thus just achieving entry block is still a good predictor for successful PVI [14,15]. The 3D mapping system is a very useful tool in AF interventional treatment. Not only does it guide the ablation line, but also significantly reduces fluoroscopy time, as many catheter maneuvers can be done by observing its movement solely on the 3D map. Latest software solutions help to evaluate the ablation line by color-coding lesion parameters such as catheter stability, time spent in one spot and contact force on the map (VisiTagTM Module, CARTO3, Biosense Webster).
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Balloon cryoablation
Balloon cryoablation of PV is a very popular technique of PV isolation as it reduces the time of the procedure and requires less catheter maneuvers than the point-by-point RF ablation. The catheter used in this method is provided with an inflatable balloon near the distal end (Arctic FrontTM , Cryocath, Medtronic) (FIGURE 5). The balloon is designed to be placed in the PV ostia through the transseptal approach. The location is confirmed by fluoroscopic view and contrast injection distal to the balloon. When the contact of the balloon with the muscular tissue in the PV ostium is proper, the injected contrast is not flushed back to the atrium and stays in the PV. Then, the balloon is filled with nitrous oxide, thus freezing the surrounding tissue. In the optimal occlusion of PV ostium, the temperature of the balloon will drop below –40 to even –70˚C. Each pulmonary vein is frozen at least twice for 4 min. It is essential to monitor the function of phrenic nerve during the isolation of right-sided PV as the phrenic nerve palsy occurs more often during cryoablation than during RF. Accepted methods of phrenic nerve monitoring are: periodic pacing from superior vena cava (e.g., every 3 s) and observing the force of diaphragm contractions; periodic verification of right diaphragm movement under fluoroscopy. If a phrenic nerve palsy occurs, freezing must be stopped immediately to prevent permanent damage to the nerve. Usually, the palsy is temporary and subsides in a few hours. Occasionally, it may remain for months impairing patient’s exercise capacity. After the cryoablation, the veins should be checked for electrical activity with a circular diagnostic catheter. If pulmonary vein potentials are registered, the target vein may be frozen again. A very convenient solution is to use a dedicated, small ‘lasso’ catheter that serves also as a leader to intubate the veins ostia (AchieveTM , Medtronic). Such catheter is advanced through the balloon catheter shaft and allows to observe PVP’s disappearance during cryoablation. The first generation of cryoballoon was evaluated in a randomized controlled trial ‘Sustained Treatment of Paroxysmal Atrial Fibrillation’. Its efficacy was comparable to RF ablation (69.9% patients free from AF in 1-year follow-up) [16]. In 2013, the second generation of cryoballoon was developed (Arctic Front AdvanceTM , Cryocath, Medtronic) that has already been proven to be even more effective. In recently published trials, the authors present 78–84% treatment success in informahealthcare.com
Figure 2. Loop-shaped catheter for mapping pulmonary veins ostia for breakthroughs and pulmonary vein potentials.
12-month observation [17–19]. However, the occurrence of phrenic nerve palsy has increased nearly twice to 8–19%. The proper assessment of PV anatomy is crucial before balloon cryoablation. Common PV ostium, too large or too small
Figure 3. 3D map of left atrium and pulmonary veins created with the use of CARTOÒ3, Biosense Webster. Color-coding of lesion parameters with the use of VisiTagTM Module. Image provided courtesy of Biosense Webster.
597
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Review
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
Webster, BardÒ HD Mesh Ablator Catheter, Boston Scientific, Marlborough, MA, USA) that creates a circular or crescent-shaped lesion (FIGURES 6 & 7) [9,10,20]. Besides ablation multi-electrode catheter can also pace and register local electrical signals. Therefore, there is no need to advance another catheter into the LA. Its variable loop shape fits into different veins sizes. When positioned in the PV ostium, the ablation can be done with the use of all pole pairs at once or selectively. Usually each vein needs several, 1-min applications. Between subsequent applications, operator rotates the catheter slightly to make sure the circular lesion is complete. If the pulmonary vein potentials are still present, the ablation can be repeated with exclusive use of the electrodes that register the PVPs, thus reducing the unnecessary scaring of the rest of the Figure 4. 3D map of left atrium and pulmonary veins ostia created with EnSite, tissue. Recently designed nMARQ (BioJude Medical. Image provided courtesy of St. Jude Medical, Inc. sense Webster) catheter adds the ability to create electroanatomical map and naviveins, asymmetric ostia may limit the procedure efficacy. It is gate with the 3D non-fluoroscopic system CARTO3. Moreadvised to always perform CT or MR scan of LA and PV over, it provides cooling with irrigation technology [10]. before qualifying patient to balloon cryoablation. Multi-electrode RF catheter ablation has proven to be similarly efficient as point-by-point ablation in preserving sinus Multi-electrode RF catheter ablation rhythm during 6-month follow-up [21], while significantly To shorten the RF ablation, one can use a multi-electrode RF reducing procedure and fluoroscopy time. However, anatomical catheter (PVAC, Medtronic, MN, USA; nMARQTM , Biosense variants like large vein ostia (diameter over 24 mm) or separate right middle pulmonary vein tend to decrease the efficacy of this approach [22]. Moreover, there are few studies that demonstrate significantly increased risk of asymptomatic intracranial embolic events following multi-electrode RF ablation compared with conventional irrigated RF ablation and cryoballoon [23,24]. Visually guided laser balloon ablation
One of the innovative devices used for PVI is the visually guided laser balloon catheter (CardioFocus, Marlborough, MA, USA). This catheter is provided with an inflatable balloon of variable diameter on its distal end. The balloon proximal portion contains a 2F endoscope that offers real-time visualization of the ablation region. The catheter is advanced through a deflectable sheath and, after proper positioning in the PV ostium, ablation is performed with the use of laser energy. Real-time visualization allows constant observation of the tissue contact during lesion formation that can be useful particularly in patients with complex PV anatomy. Multi-center studies report that the PVI can be achieved with the use of visually guided laser balloon with efficacy similar to RF method [11,12]. Figure 5. Arctic Front Advance Cryoablation Balloon Catheter, Cryocath, Medtronic. Image provided courtesy of Medtronic.
598
Ganglionated plexi ablation – pulmonary vein denervation
The pulmonary vein denervation by ablation of vagal ganglia performed as an addition to the PVI was proven to decrease Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
Review
Downloaded by [National Taiwan University] at 08:06 01 July 2015
arrhythmia recurrence [25–27]. The autonomic ganglionated plexi may be identified by evoking vagal reflexes (e.g., sinus bradycardia, asystole, AV block, hypotension) during first seconds of ablation [26]. The ganglia are ablated in their presumed anatomical locations outside the junctions of PV and LA. The ablation may be performed with standard, irrigated catheter used for circumferential ablation of PV. In a trial performed by Katritsis et al., additional ganglionated plexi ablation reduced the AF recurrence in 12-month follow-up from 54.5 to 26.5% [27]. Pokushalov et al. reported that the ganglionated plexi ablation alone, without additional circumferential PV isolation, may be an efficient treatment for paroxysmal AF. From 58 patients who underwent only ganglionated plexi ablation, 86.2% were free from arrhythmia in 7-month follow-up [25]. Renal denervation
Hypertension is a known risk factor for AF itself and for recurrences of arrhythmia after AF ablation. Patients with coexisting AF and resistant hypertension may benefit from concomitant PVI and renal denervation not only in terms of blood pressure reduction, but also in limiting AF episodes. In a randomized, prospective study, renal denervation added to the PVI doubled the success rate of AF ablation [28]. This approach needs further studies, especially in light of recent concerns regarding the renal denervation procedure itself. Focal impulse & rotor modulation
Focal impulse and rotor modulation (FIRM) is a substrate-based approach to the AF ablation dedicated for treatment of nonparoxysmal AF. It involves identifying rotors and focal sources that are believed to incite and perpetuate AF. It is done by computational mapping based on data collected from 3D multipolar basket catheter, which is advanced and expanded in the atrium. The largest basket catheter is fitted with 64 poles (FIRMapTM , RhythmViewTM , Topera Inc., Palo Alto, CA, USA) and can map the whole chamber at once. After localizing the rotors or focal sources, RF ablation is performed in the area. FIRM ablation combined with the PVI was found to improve outcome of the AF ablation procedure [29]. Currently, the trial called PRECISE-PAF (Precise Rotor Elimination without Concomitant pulmonary vein Isolation for the Successful Elimination of Paroxysmal AF) is being conducted which is designed to answer the question whether FIRM ablation alone, without concomitant PVI, can constitute an efficient method of AF treatment.
Figure 6. PVAC – phased radiofrequency, circular catheter for pulmonary veins isolation, Medtronic. Image provided courtesy of Medtronic.
(Hansen Medical Inc., Mountain View, CA, USA) and AmigoTM (Catheter Robotics, Inc., Mount Olive, NJ, USA). These systems include a robotic arm attached to the operating table, which directly control the ablation catheter [32,33]. The physician steers the arm with a remote controller from the control room. All of these devices improve catheter stability and precision as well as allow the operator to move away from the x-ray source. The way to reduce the radiation exposure both to the physician and the patient is the use of a 3D visualization system with live navigation. The MediGuideTM (St. Jude Medical) system integrates the 3D electromagnetic system with pre-recorded fluoroscopic cine loop. The catheter position registered by the nonfluoroscopic 3D system is applied to the pre-recorded fluoroscopic cine loop background in two standard projections. The recording is synchronized with patient’s ECG and played on the screen simulating constant fluoroscopy. This technology allows to significantly reduce radiation exposure duration during AF ablation [34].
Robotic navigation & minimizing radiation exposure
Conventional AF ablation usually requires a significant time of fluoroscopy. Robotic navigation systems were developed to reduce the physician radiation exposure and aid in catheter maneuvering. The Remote Magnetic Navigation developed by Stereotaxis Inc. (St. Louis, MI, USA) provides the ability to steer the distal tip of the catheter with a magnetic field from the control room [30,31]. The great advantage of magnetic navigation is minimizing the risk of perforation of the heart muscle through the use of soft catheters. Other popular robotic remote catheter systems are SenseiÒ X informahealthcare.com
Figure 7. Multi-ablation catheter nMARQTM (Biosense Webster). Image provided courtesy of Biosense Webster.
599
Review
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
Efficacy of paroxysmal AF ablation
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Ablation has proven to be a successful method of managing paroxysmal AF. The 2012 Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society Expert Consensus Statement on Catheter and Surgical Ablation of AF provided several AF ablation success definitions [35]: • Acute procedural success – electrical isolation of all PV confirmed by at least entrance block; • One-year success – freedom from AF, atrial flutter and atrial tachycardia episodes lasting more than 30 s without AAD therapy assessed from the end of 3-month blanking period to 1 year after the procedure; • Long-term success – freedom from AF, atrial flutter and atrial tachycardia episodes lasting more than 30 s without AAD therapy (class I and III) assessed from the end of 3-month blanking period to 36 months after the procedure. Blanking period of 3 months is applied to exclude early recurrences of AF, which in most cases do not imply treatment failure. Minimum follow-up screening for paroxysmal AF recurrence should include: standard 12-lead ECG on every follow-up visit (every 3–6 months); 24-h Holter-ECG at the end of follow-up period and ECG recording during symptoms. A very effective method of arrhythmia recurrence detection is the measurement of AF burden in patients with cardiac implantable electrical devices (pacemaker, loop recorder, implantable cardioverter defibrillator). Intermittent AF burden measuring, for example, with 48–120-h Holter-ECG may provide important yet limited data. Seventy-five percent or greater reduction in the number or duration of AF episodes as well as the percentage of time a patient spends in AF is considered as clinical/partial success of AF ablation. Most AF recurrences occur in the first 12 months following the procedure; therefore, most trials accepted 1-year success as the definition of successful catheter ablation. Recent years provided few randomized controlled trials that evaluated the success of single RF catheter ablation of AF during 9–12 months follow-up [36–38]. The success rate varied from 66 to 89%. The Sustained Treatment of Paroxysmal Atrial Fibrillation randomized controlled trials concerning efficacy of cryoballoon PV ablation reported the success rate of 69.9% at 12-month follow-up. However, in this trial the first generation cryoballoon was used [16]. Recent trials regarding second-generation cryoballoon report 1-year AF-free survival in 83–84% patients after a single procedure [17–19]. Long-term outcomes after single AF ablation procedure vary. In the recent years, few trials with 5-year follow-up period were published. The authors present long-term efficacy of single ablation procedure between 29 and 53.2% [39–41]. When considering multiple procedures, the success rate rises up to nearly 80% [42]. The follow-up data differ in various studies due to several factors. First, the groups are not homogenous concerning sex, age, co-morbidities and LA diameter. Not to be neglected is the method and frequency of rhythm control. The 12-lead ECG performed once every follow-up visit is definitely less sensitive in AF detection than, for example, implantable loop 600
recorder or event monitor. AF recurrences are also related to hypertension, nicotine intake, obesity, hyperglycemia, coronary artery disease and left ventricle ejection fraction. The manner of managing all these factors significantly affect the long-term results of AF catheter ablation. Proper patient assessment prior to the ablation is essential. The procedure efficacy will be significantly limited in patients with enlarged LA (anterior-posterior diameter over 5 cm), unstable hypertension and advanced age (over 70 years old). It is advised to perform transesophageal echocardiography, computed tomography or MR scan of the LA and PV ostia to evaluate their anatomy and choose the best ablation method for each patient individually. Managing persistent & long-standing AF
The persistent and long-standing AF is still a challenge as the ablation results are poor. Early studies evaluated success rate of non-paroxysmal atrial fibrillation ablation to 40%. That clearly exhibits that PVI is not enough to manage persistent AF as the arrhythmia substrate is no longer solely in the PV. One of the attempts to map the electrophysiological substrate of AF was to locate and ablate areas where complex fractioned electrograms (CFAE) are recorded [8]. Nademanee et al. explained that CFAE correlate with areas of slow conduction and pivot points of reentrant wavelets. The Substrate and Trigger Ablation for Reduction of AF study has confirmed positive effect of compiling PVI and CFAE ablation, increasing the success rate by nearly 30% when compared with PVI or CFAE ablation alone [43]. Other approach involves linear ablation of LA. Most popular line localizations are the LA roof and the mitral isthmus. In 2010, the Substrate and Trigger Ablation for Reduction of AF II study was started, which was designed to compare PVI, PVI + CFAE and PVI + Lines methods for managing persistent AF [44]. At the moment, the study results are being analyzed and there is hope it will shed some light on non-paroxysmal AF ablation methods. Another approach to long-standing persistent AF is the ablation of ganglionated plexi [45]. Single ablation of autonomic plexi provided sinus rhythm maintenance in only 38.2% patients in 24-month follow-up, but after repeated procedure and circumferential PV isolation, the success rate increased to 59.6% in 16 ± 7 months follow-up. Conclusion
Ablation has become the standard treatment for paroxysmal AF. The European Society of Cardiology guidelines updated in 2012 recommend catheter ablation in symptomatic, recurrent, paroxysmal AF in patients who are suffering from arrhythmia despite taking AAD (IA) [46]. Catheter ablation should be also considered as first-line therapy in selected patients with symptomatic paroxysmal AF as an alternative to AAD considering patient choice, benefit and risk (IIa). It is a repeatable procedure with high success rate and low rate of complications, limited to 4.5% total and 1.7% major (stroke, cardiac tamponade, death) [47]. New methods and tools to make the AF ablation more successful, precise as well as safer and quicker are Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
constantly being developed. The ablation of persistent and long-standing AF remains the challenge.
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Expert commentary
AF ablation is definitely the most intensively developed field of electrophysiology. AF is already the most common arrhythmia and its incidence will increase each year as the world’s population gets older. The success rate of paroxysmal AF ablation in patients without additional diseases is high. Over the years, this procedure has become safer and more accessible due to duration reduction and development of novel devices. The guidelines recommend AF ablation in patients suffering from paroxysmal AF despite taking AAD (IA) or even as a first-line therapy in selected ones (IIA). The efficacy of persistent and long-standing AF ablation leaves much to be desired. The recurrence rate is still high and there is a need to develop new tools and methods to deal with these patients. Five-year view
Contemporary classic methods of paroxysmal AF ablation are successful and safe when performed by an experienced operator. However, it takes a significant amount of time to master it. Moreover, the procedure duration usually exceeds 2 h that further limits its accessibility. The ‘single-shot’ methods like balloon cryoablation, multi-ablation RF catheters and laser balloon ablation are the response to the need for easier and quicker methods of paroxysmal AF ablation. These tools are
Review
likely to be developed further in the forthcoming years as they provide wider access to the AF ablation for both patients and operators. The role of autonomic system in AF triggering and maintenance is known to a limited extent. The positive results of ganglia ablation and renal denervation procedures confirm that modulation of autonomic system is not to be neglected in future interventional treatment of AF. Substrate-based approach remains the hot topic in AF ablation as the results of persistent and long-standing AF are poor. Novel devices support the operators with computational tools to map the rotors and focal sources that drive AF. The preliminary results of CFAE and FIRM ablations were very promising and we hope that ongoing trials will confirm these methods as safe and efficient solutions for large number of patients with persistent and long-lasting AF. Financial & competing interests disclosure
K Kaczmarek has received a research grant from Biosense Webster and is on the advisory board for Boston Scientific. L Szumowski has received research grants from Biosense Webster, Biotronik and Medtronic. P Ptaszynski has received research grants from Biosense Webster and Medtronic, as well as a research fellowship from St Jude Medical. He is also on the advisory board for Biosense Webster. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.
Key issues • Atrial fibrillation (AF) is the most common sustained arrhythmia and a major cause of stroke. • Catheter ablation is a safe and efficient method of interventional treatment of AF. • Ablation of paroxysmal AF generally focuses on electrical isolation of pulmonary veins from left atrium. • New methods of ‘single-shot’ pulmonary veins isolation – balloon cryoablation, circular radiofrequency catheter, visually guided laser balloon ablation are promising and help to make the procedure more efficient, quicker and easier. • Robotic navigation systems provide better catheter stability and allow the physician to move away from x-ray source. • Ablation of autonomic ganglia of left atrium added to the pulmonary vein isolation increases the procedure efficacy. • Catheter ablation in persistent and long-standing AF is still not as effective as in the paroxysmal AF. • Complex fractioned electrograms ablation, ganglionated plexi ablation and focal impulse and rotor modulation are ‘gleam of hope’ for patients with persistent and long-standing AF. • The next few years will provide us with the results of many important trials that will define the direction of development of AF ablation techniques.
References 1.
2.
Camm AJ, Kirchhof P, Lip GY, et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369-429 Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation in adults. JAMA 2001;285:2370
informahealthcare.com
3.
4.
5.
Jais P, Haissaguerre M, Shah DC, et al. A focal source of atrial fibrillation treated by discrete radiofrequency ablation. Circulation 1997;95:572-6 Haissaguerre M, Jaı¨s P. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659-66 Haı¨ssaguerre M, Shah DC, Jaı¨s P, et al. Electrophysiological breakthroughs from the
left atrium to the pulmonary veins. Circulation 2000;102:2463-5 6.
Pappone C, Rosanio S, Oreto G, et al. Circumferential Radiofrequency Ablation of Pulmonary. Circulation 2000;102:2619-28
7.
Ouyang F, Ba¨nsch D, Ernst S, et al. Complete isolation of left atrium surrounding the pulmonary veins: new insights from the double-Lasso technique in paroxysmal atrial fibrillation. Circulation 2004;110:2090-6
601
Review 8.
Nademanee K, McKenzie J, Kosar E, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol 2004;43:2044-53
9.
Boersma LV, Wijffels MC, Oral H, et al. Pulmonary vein isolation by duty-cycled bipolar and unipolar radiofrequency energy with a multielectrode ablation catheter. Heart Rhythm 2008;5:1635-42
10.
11.
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
12.
13.
procedure cryoballoon ablation: a comparison between the first and second generation balloon. J Cardiovasc Electrophysiol 2014. [Epub ahead of print] 20.
21.
Shin DI, Kirmanoglou K, Eickholt C, et al. Initial results of using a novel irrigated multielectrode mapping and ablation catheter for pulmonary vein isolation. Heart Rhythm 2014;11:375-83 Dukkipati SR, Neuzil P, Kautzner J, et al. The durability of pulmonary vein isolation using the visually guided laser balloon catheter: multicenter results of pulmonary vein remapping studies. Heart Rhythm 2012;9:919-25
22.
Dukkipati SR, Kuck KH, Neuzil P, et al. Pulmonary vein isolation using a visually guided laser balloon catheter: the first 200-patient multicenter clinical experience. Circ Arrhythm Electrophysiol 2013;6: 467-72
23.
Demazumder D, Mirotznik MS, Schwartzman D. Biophysics of radiofrequency ablation using an irrigated electrode. J Interv Card Electrophysiol 2001;5:377-89
24.
De Filippo P, He DS, Brambilla R, et al. Clinical experience with a single catheter for mapping and ablation of pulmonary vein ostium. J Cardiovasc Electrophysiol 2009;20:367-73 Bulava A, Hanisˇ J, Sitek D, et al. Catheter ablation for paroxysmal atrial fibrillation: a randomized comparison between multielectrode catheter and point-by-point ablation. Pacing Clin Electrophysiol 2010;33:1039-46 Mulder AA, Wijffels MC, Wever EF, et al. Pulmonary vein anatomy and long-term outcome after multi-electrode pulmonary vein isolation with phased radiofrequency energy for paroxysmal atrial fibrillation. Europace 2011;13:1557-61 Gaita F, Leclercq JF, Schumacher B, et al. Incidence of silent cerebral thromboembolic lesions after atrial fibrillation ablation may change according to technology used: comparison of irrigated radiofrequency, multipolar nonirrigated catheter and cryoballoon. J Cardiovasc Electrophysiol 2011;22:961-8 Herrera Siklo´dy C, Deneke T, Hocini M, et al. Incidence of asymptomatic intracranial embolic events after pulmonary vein isolation: comparison of different atrial fibrillation ablation technologies in a multicenter study. J Am Coll Cardiol 2011;58:681-8
14.
Gerstenfeld EP, Dixit S, Callans D, et al. Utility of exit block for identifying electrical isolation of the pulmonary veins. J Cardiovasc Electrophysiol 2002;13:971-9
15.
Duytschaever M, De Meyer G, Acena M, et al. Lessons from dissociated pulmonary vein potentials: entry block implies exit block. Europace 2013;15:805-12
25.
Pokushalov E, Turov A, Shugayev P, et al. Catheter ablation of left atrial ganglionated plexi for atrial fibrillation. Asian Cardiovasc Thorac Ann 2008;16:194-201
16.
Packer DL, Kowal RC, Wheelan KR, et al. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol 2013;61:1713-23
26.
Pappone C, Santinelli V, Manguso F, et al. Pulmonary vein denervation enhances long-term benefit after circumferential ablation for paroxysmal atrial fibrillation. Circulation 2004;109:327-34
27.
Katritsis DG, Giazitzoglou E, Zografos T, et al. Rapid pulmonary vein isolation combined with autonomic ganglia modification: a randomized study. Heart Rhythm 2011;8:672-8
28.
Pokushalov E, Romanov A, Corbucci G, et al. A randomized comparison of pulmonary vein isolation with versus without concomitant renal artery denervation in patients with refractory symptomatic atrial fibrillation and resistant hypertension. J Am Coll Cardiol 2012;60: 1163-70
17.
Chierchia GB, Di Giovanni G, Ciconte G, et al. Second-generation cryoballoon ablation for paroxysmal atrial fibrillation: 1-year follow-up. Europace 2014;16:639-44
18.
Fu¨rnkranz A, Bordignon S, Dugo D, et al. Improved 1-year clinical success rate of pulmonary vein isolation with the second-generation cryoballoon in patients with paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 2014. [Epub ahead of print]
19.
Giovanni G DI, Wauters K, Chierchia GB, et al. One-year follow-up after single
602
29.
Narayan SM, Krummen DE, Shivkumar K, et al. Treatment of atrial fibrillation by the ablation of localized sources: CONFIRM (Conventional Ablation for Atrial Fibrillation with or Without Focal Impulse and Rotor Modulation) trial. J Am Coll Cardiol 2012;60:628-36
30.
Pappone C, Vicedomini G, Manguso F, et al. Robotic magnetic navigation for atrial fibrillation ablation. J Am Coll Cardiol 2006;47:1390-400
31.
Shurrab M, Danon A, Lashevsky I, et al. Robotically assisted ablation of atrial fibrillation: a systematic review and meta-analysis. Int J Cardiol 2013;169: 157-65
32.
Bai R, DI Biase L, Valderrabano M, et al. Worldwide experience with the robotic navigation system in catheter ablation of atrial fibrillation: methodology, efficacy and safety. J Cardiovasc Electrophysiol 2012;23: 820-6
33.
Khan EM, Frumkin W, Ng GA, et al. First experience with a novel robotic remote catheter system: AmigoTM mapping trial. J Interv Card Electrophysiol 2013;37:121-9
34.
Sommer P, Richter S, Hindricks G, et al. Non-fluoroscopic catheter visualization using MediGuideTM technology: experience from the first 600 procedures. J Interv Card Electrophysiol 2014. [Epub ahead of print]
35.
Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report. Heart Rhythm 2012;9: 632-96.e21
36.
Noheria A, Kumar A, Wylie J V, et al. Catheter ablation vs antiarrhythmic drug therapy for atrial fibrillation: a systematic review. Arch Intern Med 2008;168:581-6
37.
Wilber DJ, Neuzil P, De Paola A, et al. Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial. JAMA 2010;303:333-40
38.
Jaı¨s P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation: the A4 study. Circulation 2008;118:2498-505
39.
Ouyang F, Tilz R, Chun J, et al. Long-term results of catheter ablation in paroxysmal atrial fibrillation: lessons from a 5-year follow-up. Circulation 2010;122:2368-77
Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
40.
Bertaglia E, Tondo C, De Simone A, et al. Does catheter ablation cure atrial fibrillation? Single-procedure outcome of drug-refractory atrial fibrillation ablation: a 6-year multicentre experience. Europace 2010;12:181-7
41.
Weerasooriya R, Khairy P, Litalien J, et al. Catheter ablation for atrial fibrillation: are results maintained at 5 years of follow-up? J Am Coll Cardiol 2011;57:160-6 Ganesan AN, Shipp NJ, Brooks AG, et al. Long-term outcomes of catheter ablation of atrial fibrillation: a systematic review and meta-analysis. J Am Heart Assoc 2013;2: e004549
Verma A, Mantovan R, Macle L, et al. Substrate and Trigger Ablation for Reduction of Atrial Fibrillation (STAR AF): a randomized, multicentre, international trial. Eur Heart J 2010;31:1344-56
44.
Verma A, Sanders P, Macle L, et al. Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II (STAR AF II): design and rationale. Am Heart J 2012(164):1-6.e6
45.
Pokushalov E, Romanov A, Artyomenko S, et al. Ganglionated plexi ablation for longstanding persistent atrial fibrillation. Europace 2010;12:342-6
46.
Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J 2012;33:2719-47
47.
Cappato R, Calkins H, Chen SA, et al. Updated worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circ Arrhythm Electrophysiol 2010;3:32-8
Downloaded by [National Taiwan University] at 08:06 01 July 2015
42.
43.
Review
informahealthcare.com
603
Expert Review of Medical Devices Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ierd20
Interventional treatment of atrial fibrillation – contemporary methods and perspectives a
b
c
d
Bartosz Zuchowski , Krzysztof Kaczmarek , Lukasz Szumowski , Yi-Gang Li & Pawel Ptaszynski
b
a
Department of Cardiology-Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland b
Department of Electrocardiology, Medical University, Regional Sterling Heart Disease Center, Sterling 1/3 91–425 Lodz, Poland c
Department of Arrhythmias, National Institute of Cardiology, Warsaw, Poland
d
Department of Cardiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medine, 200092, Shanghai, China Published online: 29 Apr 2015.
To cite this article: Bartosz Zuchowski, Krzysztof Kaczmarek, Lukasz Szumowski, Yi-Gang Li & Pawel Ptaszynski (2014) Interventional treatment of atrial fibrillation – contemporary methods and perspectives, Expert Review of Medical Devices, 11:6, 595-603 To link to this article: http://dx.doi.org/10.1586/17434440.2014.941810
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Review
Interventional treatment of atrial fibrillation – contemporary methods and perspectives Downloaded by [National Taiwan University] at 08:06 01 July 2015
Expert Rev. Med. Devices 11(6), 595–603 (2014)
Bartosz Zuchowski1, Krzysztof Kaczmarek2, Lukasz Szumowski3, Yi-Gang Li4 and Pawel Ptaszynski*2 1 Department of Cardiology-Intensive Therapy, Poznan University of Medical Sciences, Poznan, Poland 2 Department of Electrocardiology, Medical University, Regional Sterling Heart Disease Center, Sterling 1/3 91–425 Lodz, Poland 3 Department of Arrhythmias, National Institute of Cardiology, Warsaw, Poland 4 Department of Cardiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medine, 200092, Shanghai, China *Address for correspondence: Tel.: +48 426 644 304 Fax: +48 426 644 269 [email protected]
informahealthcare.com
Atrial fibrillation (AF) is estimated to affect nearly 3 million people around the world. It is the most common arrhythmia and its incidence increases with age. Catheter ablation is an interventional procedure performed to reduce the patient’s AF burden when pharmacotherapy did not succeed in relieving the patient’s symptoms. The ablation is most effective in paroxysmal AF; however, many techniques are being developed to make this procedure more eligible for patients with persistent arrhythmia. The most common AF ablation technique involves separating electric activity of the pulmonary veins from the left atrium. Over recent years, many novel and promising techniques were developed (e.g., balloon cryoablation, circular catheter ablation, laser ablation, robotic navigation, etc.), which may further improve AF ablation efficacy. KEYWORDS: arrhythmia • atrial fibrillation • catheter ablation • cryoablation • interventional treatment • laser ablation • radiofrequency ablation
Atrial fibrillation (AF) is the most common sustained arrhythmia and a major cause of stroke. According to current estimates, nearly 3 million people suffer from AF. Its incidence increases with age, about 10% of patients aged 80 years or older suffer from AF [1,2]. Among its main risk factors are: hypertension, coronary artery disease, heart valves disorders, thyroid diseases, family AF history, alcohol and nicotine intake. AF significantly increases mortality (double in patients without anticoagulation treatment) and hospitalization rate while decreasing quality of life and exercise capacity. Its ‘natural’ course begins with short, rare, paroxysmal episodes of arrhythmia that gradually become more frequent and longer. Over time, the AF episodes become persistent and require hospitalization in order to perform cardioversion or administer intravenous drugs to interrupt the arrhythmia, finally leading to the permanent form where even cardioversion does not succeed in converting to sinus rhythm. Pharmacological treatment focuses on reducing the thromboembolic risk by oral anticoagulation and using antiarrhythmic drugs (AAD) to reduce AF recurrence and control the heart rate in permanent AF form. By the end of the 10.1586/17434440.2014.941810
20th century, new interventional methods of AF treatment were developed. History
In 1997, Haı¨ssaguerre performed the first percutaneous ablation of focal origin of AF [3]. In 1998, pulmonary veins (PV) were identified as the most important source of ectopic beats, which initiate paroxysmal AF [4]. Over the next few years, different ablation techniques were developed to electrically isolate PV from left atrium (LA) [5–12]. At the present time, we have advanced techniques of pulmonary vein isolation (PVI), which make the procedure more successful, quicker and simpler, while still following the same idea, that is, to eliminate electrical connections between the PV and LA, which allow PV potentials to enter the LA and trigger AF paroxysm. Contemporary techniques Radiofrequency ablation of electrophysiological breakthroughs
Principals of this technique were published by Haı¨ssaguerre et al. in 2000 [5]. It requires the use of a circular, multi-polar diagnostic catheter to map the PV for electrical connections called ‘breakthroughs’. This loop-shaped catheter is
Ó 2014 Informa UK Ltd
ISSN 1743-4440
595
Review
I
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
08
08.50
09
09.50
10
10.50
11
III V1 V4 HIS 1-2
CS 1-2 L 1-2
Downloaded by [National Taiwan University] at 08:06 01 July 2015
L 2-3 L 3-4 L 4-5 L 5-6 L 6-7 L 7-8 L 8-9 L 9-10 ABL 1-2
Figure 1. Pulmonary vein potentials recorded by poles L4–L8 of circular catheter in the ostium of left superior pulmonary vein during atrial fibrillation.
introduced into the LA through the transseptal approach (through either a patent foramen ovale or by a transseptal puncture) and positioned sequentially in the proximal part of every pulmonary vein to map them for pulmonary vein muscle potentials (PVPs) (FIGURES 1 & 2). The radiofrequency (RF) ablation catheter is also advanced through the transseptal route. The target for ablation is the muscular tissue at the pulmonary vein ostium where the earliest PVPs are recorded. Usually, there is more than one breakthrough and the subsequent ones tend to appear once the first one is ablated. The locating of breakthroughs is performed both during sinus rhythm and left atrial pacing (from catheter placed in distal coronary sinus region). The ablation must be performed as proximally as possible to prevent PV stenosis. In most cases, irrigated RF ablation catheters are used as they create wider and deeper lesions and reduce the risk of thrombus formation [13]. The end point of ablation in this technique is the elimination of PVP conduction to the atria. Circumferential RF ablation of pulmonary vein ostia
Circumferential PV isolation was developed by Pappone et al. in 2000 [6]. The technique involves the creation of a circular, continuous lesion around the PV ostia in order to isolate the PVs from the atrium. It implicates the use of 3D 596
electroanatomic navigation system (CARTOÒ3, Biosense Webster, Diamond Bar, CA, USA; EnSite Velocity, St. Jude Medical, St. Paul, MN, USA) to map the PV ostia and keep the ablation line continuous (FIGURES 3 & 4). The end point of the ablation in this approach is the creation of circumferential, continuous lines of conduction block around every PV. Contemporary, mixed RF approach
At the present time, RF circumferential PVI with the use of 3D mapping system is still widely used. However in addition, the multi-polar circular diagnostic catheter (commonly called ‘Lasso’) is used to check whether there are any breakthroughs present after PVI. If there are, focal RF ablation at the site of earliest pulmonary vein potential is applied. Usage of irrigated catheters is the standard. The PV may be isolated one by one or both ipsilateral at a time, for example, with the use of Double-Lasso technique [7]. Established end point in AF ablation is to achieve a bidirectional block between left-atrium and PV. The entry block (LAPV) is assessed by elimination or dissociation of pulmonary vein potentials on the circular mapping catheter located in the PV ostium during sinus rhythm and pacing from coronary sinus. The exit block (PV-LA) is evaluated by pacing from inside the Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
Review
pulmonary vein distal to the ablation line. If the pacing does not affect the atrial rhythm, the exit block is present. In fact, the unidirectional LA-PV block is very rare, thus just achieving entry block is still a good predictor for successful PVI [14,15]. The 3D mapping system is a very useful tool in AF interventional treatment. Not only does it guide the ablation line, but also significantly reduces fluoroscopy time, as many catheter maneuvers can be done by observing its movement solely on the 3D map. Latest software solutions help to evaluate the ablation line by color-coding lesion parameters such as catheter stability, time spent in one spot and contact force on the map (VisiTagTM Module, CARTO3, Biosense Webster).
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Balloon cryoablation
Balloon cryoablation of PV is a very popular technique of PV isolation as it reduces the time of the procedure and requires less catheter maneuvers than the point-by-point RF ablation. The catheter used in this method is provided with an inflatable balloon near the distal end (Arctic FrontTM , Cryocath, Medtronic) (FIGURE 5). The balloon is designed to be placed in the PV ostia through the transseptal approach. The location is confirmed by fluoroscopic view and contrast injection distal to the balloon. When the contact of the balloon with the muscular tissue in the PV ostium is proper, the injected contrast is not flushed back to the atrium and stays in the PV. Then, the balloon is filled with nitrous oxide, thus freezing the surrounding tissue. In the optimal occlusion of PV ostium, the temperature of the balloon will drop below –40 to even –70˚C. Each pulmonary vein is frozen at least twice for 4 min. It is essential to monitor the function of phrenic nerve during the isolation of right-sided PV as the phrenic nerve palsy occurs more often during cryoablation than during RF. Accepted methods of phrenic nerve monitoring are: periodic pacing from superior vena cava (e.g., every 3 s) and observing the force of diaphragm contractions; periodic verification of right diaphragm movement under fluoroscopy. If a phrenic nerve palsy occurs, freezing must be stopped immediately to prevent permanent damage to the nerve. Usually, the palsy is temporary and subsides in a few hours. Occasionally, it may remain for months impairing patient’s exercise capacity. After the cryoablation, the veins should be checked for electrical activity with a circular diagnostic catheter. If pulmonary vein potentials are registered, the target vein may be frozen again. A very convenient solution is to use a dedicated, small ‘lasso’ catheter that serves also as a leader to intubate the veins ostia (AchieveTM , Medtronic). Such catheter is advanced through the balloon catheter shaft and allows to observe PVP’s disappearance during cryoablation. The first generation of cryoballoon was evaluated in a randomized controlled trial ‘Sustained Treatment of Paroxysmal Atrial Fibrillation’. Its efficacy was comparable to RF ablation (69.9% patients free from AF in 1-year follow-up) [16]. In 2013, the second generation of cryoballoon was developed (Arctic Front AdvanceTM , Cryocath, Medtronic) that has already been proven to be even more effective. In recently published trials, the authors present 78–84% treatment success in informahealthcare.com
Figure 2. Loop-shaped catheter for mapping pulmonary veins ostia for breakthroughs and pulmonary vein potentials.
12-month observation [17–19]. However, the occurrence of phrenic nerve palsy has increased nearly twice to 8–19%. The proper assessment of PV anatomy is crucial before balloon cryoablation. Common PV ostium, too large or too small
Figure 3. 3D map of left atrium and pulmonary veins created with the use of CARTOÒ3, Biosense Webster. Color-coding of lesion parameters with the use of VisiTagTM Module. Image provided courtesy of Biosense Webster.
597
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Review
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
Webster, BardÒ HD Mesh Ablator Catheter, Boston Scientific, Marlborough, MA, USA) that creates a circular or crescent-shaped lesion (FIGURES 6 & 7) [9,10,20]. Besides ablation multi-electrode catheter can also pace and register local electrical signals. Therefore, there is no need to advance another catheter into the LA. Its variable loop shape fits into different veins sizes. When positioned in the PV ostium, the ablation can be done with the use of all pole pairs at once or selectively. Usually each vein needs several, 1-min applications. Between subsequent applications, operator rotates the catheter slightly to make sure the circular lesion is complete. If the pulmonary vein potentials are still present, the ablation can be repeated with exclusive use of the electrodes that register the PVPs, thus reducing the unnecessary scaring of the rest of the Figure 4. 3D map of left atrium and pulmonary veins ostia created with EnSite, tissue. Recently designed nMARQ (BioJude Medical. Image provided courtesy of St. Jude Medical, Inc. sense Webster) catheter adds the ability to create electroanatomical map and naviveins, asymmetric ostia may limit the procedure efficacy. It is gate with the 3D non-fluoroscopic system CARTO3. Moreadvised to always perform CT or MR scan of LA and PV over, it provides cooling with irrigation technology [10]. before qualifying patient to balloon cryoablation. Multi-electrode RF catheter ablation has proven to be similarly efficient as point-by-point ablation in preserving sinus Multi-electrode RF catheter ablation rhythm during 6-month follow-up [21], while significantly To shorten the RF ablation, one can use a multi-electrode RF reducing procedure and fluoroscopy time. However, anatomical catheter (PVAC, Medtronic, MN, USA; nMARQTM , Biosense variants like large vein ostia (diameter over 24 mm) or separate right middle pulmonary vein tend to decrease the efficacy of this approach [22]. Moreover, there are few studies that demonstrate significantly increased risk of asymptomatic intracranial embolic events following multi-electrode RF ablation compared with conventional irrigated RF ablation and cryoballoon [23,24]. Visually guided laser balloon ablation
One of the innovative devices used for PVI is the visually guided laser balloon catheter (CardioFocus, Marlborough, MA, USA). This catheter is provided with an inflatable balloon of variable diameter on its distal end. The balloon proximal portion contains a 2F endoscope that offers real-time visualization of the ablation region. The catheter is advanced through a deflectable sheath and, after proper positioning in the PV ostium, ablation is performed with the use of laser energy. Real-time visualization allows constant observation of the tissue contact during lesion formation that can be useful particularly in patients with complex PV anatomy. Multi-center studies report that the PVI can be achieved with the use of visually guided laser balloon with efficacy similar to RF method [11,12]. Figure 5. Arctic Front Advance Cryoablation Balloon Catheter, Cryocath, Medtronic. Image provided courtesy of Medtronic.
598
Ganglionated plexi ablation – pulmonary vein denervation
The pulmonary vein denervation by ablation of vagal ganglia performed as an addition to the PVI was proven to decrease Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
Review
Downloaded by [National Taiwan University] at 08:06 01 July 2015
arrhythmia recurrence [25–27]. The autonomic ganglionated plexi may be identified by evoking vagal reflexes (e.g., sinus bradycardia, asystole, AV block, hypotension) during first seconds of ablation [26]. The ganglia are ablated in their presumed anatomical locations outside the junctions of PV and LA. The ablation may be performed with standard, irrigated catheter used for circumferential ablation of PV. In a trial performed by Katritsis et al., additional ganglionated plexi ablation reduced the AF recurrence in 12-month follow-up from 54.5 to 26.5% [27]. Pokushalov et al. reported that the ganglionated plexi ablation alone, without additional circumferential PV isolation, may be an efficient treatment for paroxysmal AF. From 58 patients who underwent only ganglionated plexi ablation, 86.2% were free from arrhythmia in 7-month follow-up [25]. Renal denervation
Hypertension is a known risk factor for AF itself and for recurrences of arrhythmia after AF ablation. Patients with coexisting AF and resistant hypertension may benefit from concomitant PVI and renal denervation not only in terms of blood pressure reduction, but also in limiting AF episodes. In a randomized, prospective study, renal denervation added to the PVI doubled the success rate of AF ablation [28]. This approach needs further studies, especially in light of recent concerns regarding the renal denervation procedure itself. Focal impulse & rotor modulation
Focal impulse and rotor modulation (FIRM) is a substrate-based approach to the AF ablation dedicated for treatment of nonparoxysmal AF. It involves identifying rotors and focal sources that are believed to incite and perpetuate AF. It is done by computational mapping based on data collected from 3D multipolar basket catheter, which is advanced and expanded in the atrium. The largest basket catheter is fitted with 64 poles (FIRMapTM , RhythmViewTM , Topera Inc., Palo Alto, CA, USA) and can map the whole chamber at once. After localizing the rotors or focal sources, RF ablation is performed in the area. FIRM ablation combined with the PVI was found to improve outcome of the AF ablation procedure [29]. Currently, the trial called PRECISE-PAF (Precise Rotor Elimination without Concomitant pulmonary vein Isolation for the Successful Elimination of Paroxysmal AF) is being conducted which is designed to answer the question whether FIRM ablation alone, without concomitant PVI, can constitute an efficient method of AF treatment.
Figure 6. PVAC – phased radiofrequency, circular catheter for pulmonary veins isolation, Medtronic. Image provided courtesy of Medtronic.
(Hansen Medical Inc., Mountain View, CA, USA) and AmigoTM (Catheter Robotics, Inc., Mount Olive, NJ, USA). These systems include a robotic arm attached to the operating table, which directly control the ablation catheter [32,33]. The physician steers the arm with a remote controller from the control room. All of these devices improve catheter stability and precision as well as allow the operator to move away from the x-ray source. The way to reduce the radiation exposure both to the physician and the patient is the use of a 3D visualization system with live navigation. The MediGuideTM (St. Jude Medical) system integrates the 3D electromagnetic system with pre-recorded fluoroscopic cine loop. The catheter position registered by the nonfluoroscopic 3D system is applied to the pre-recorded fluoroscopic cine loop background in two standard projections. The recording is synchronized with patient’s ECG and played on the screen simulating constant fluoroscopy. This technology allows to significantly reduce radiation exposure duration during AF ablation [34].
Robotic navigation & minimizing radiation exposure
Conventional AF ablation usually requires a significant time of fluoroscopy. Robotic navigation systems were developed to reduce the physician radiation exposure and aid in catheter maneuvering. The Remote Magnetic Navigation developed by Stereotaxis Inc. (St. Louis, MI, USA) provides the ability to steer the distal tip of the catheter with a magnetic field from the control room [30,31]. The great advantage of magnetic navigation is minimizing the risk of perforation of the heart muscle through the use of soft catheters. Other popular robotic remote catheter systems are SenseiÒ X informahealthcare.com
Figure 7. Multi-ablation catheter nMARQTM (Biosense Webster). Image provided courtesy of Biosense Webster.
599
Review
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
Efficacy of paroxysmal AF ablation
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Ablation has proven to be a successful method of managing paroxysmal AF. The 2012 Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society Expert Consensus Statement on Catheter and Surgical Ablation of AF provided several AF ablation success definitions [35]: • Acute procedural success – electrical isolation of all PV confirmed by at least entrance block; • One-year success – freedom from AF, atrial flutter and atrial tachycardia episodes lasting more than 30 s without AAD therapy assessed from the end of 3-month blanking period to 1 year after the procedure; • Long-term success – freedom from AF, atrial flutter and atrial tachycardia episodes lasting more than 30 s without AAD therapy (class I and III) assessed from the end of 3-month blanking period to 36 months after the procedure. Blanking period of 3 months is applied to exclude early recurrences of AF, which in most cases do not imply treatment failure. Minimum follow-up screening for paroxysmal AF recurrence should include: standard 12-lead ECG on every follow-up visit (every 3–6 months); 24-h Holter-ECG at the end of follow-up period and ECG recording during symptoms. A very effective method of arrhythmia recurrence detection is the measurement of AF burden in patients with cardiac implantable electrical devices (pacemaker, loop recorder, implantable cardioverter defibrillator). Intermittent AF burden measuring, for example, with 48–120-h Holter-ECG may provide important yet limited data. Seventy-five percent or greater reduction in the number or duration of AF episodes as well as the percentage of time a patient spends in AF is considered as clinical/partial success of AF ablation. Most AF recurrences occur in the first 12 months following the procedure; therefore, most trials accepted 1-year success as the definition of successful catheter ablation. Recent years provided few randomized controlled trials that evaluated the success of single RF catheter ablation of AF during 9–12 months follow-up [36–38]. The success rate varied from 66 to 89%. The Sustained Treatment of Paroxysmal Atrial Fibrillation randomized controlled trials concerning efficacy of cryoballoon PV ablation reported the success rate of 69.9% at 12-month follow-up. However, in this trial the first generation cryoballoon was used [16]. Recent trials regarding second-generation cryoballoon report 1-year AF-free survival in 83–84% patients after a single procedure [17–19]. Long-term outcomes after single AF ablation procedure vary. In the recent years, few trials with 5-year follow-up period were published. The authors present long-term efficacy of single ablation procedure between 29 and 53.2% [39–41]. When considering multiple procedures, the success rate rises up to nearly 80% [42]. The follow-up data differ in various studies due to several factors. First, the groups are not homogenous concerning sex, age, co-morbidities and LA diameter. Not to be neglected is the method and frequency of rhythm control. The 12-lead ECG performed once every follow-up visit is definitely less sensitive in AF detection than, for example, implantable loop 600
recorder or event monitor. AF recurrences are also related to hypertension, nicotine intake, obesity, hyperglycemia, coronary artery disease and left ventricle ejection fraction. The manner of managing all these factors significantly affect the long-term results of AF catheter ablation. Proper patient assessment prior to the ablation is essential. The procedure efficacy will be significantly limited in patients with enlarged LA (anterior-posterior diameter over 5 cm), unstable hypertension and advanced age (over 70 years old). It is advised to perform transesophageal echocardiography, computed tomography or MR scan of the LA and PV ostia to evaluate their anatomy and choose the best ablation method for each patient individually. Managing persistent & long-standing AF
The persistent and long-standing AF is still a challenge as the ablation results are poor. Early studies evaluated success rate of non-paroxysmal atrial fibrillation ablation to 40%. That clearly exhibits that PVI is not enough to manage persistent AF as the arrhythmia substrate is no longer solely in the PV. One of the attempts to map the electrophysiological substrate of AF was to locate and ablate areas where complex fractioned electrograms (CFAE) are recorded [8]. Nademanee et al. explained that CFAE correlate with areas of slow conduction and pivot points of reentrant wavelets. The Substrate and Trigger Ablation for Reduction of AF study has confirmed positive effect of compiling PVI and CFAE ablation, increasing the success rate by nearly 30% when compared with PVI or CFAE ablation alone [43]. Other approach involves linear ablation of LA. Most popular line localizations are the LA roof and the mitral isthmus. In 2010, the Substrate and Trigger Ablation for Reduction of AF II study was started, which was designed to compare PVI, PVI + CFAE and PVI + Lines methods for managing persistent AF [44]. At the moment, the study results are being analyzed and there is hope it will shed some light on non-paroxysmal AF ablation methods. Another approach to long-standing persistent AF is the ablation of ganglionated plexi [45]. Single ablation of autonomic plexi provided sinus rhythm maintenance in only 38.2% patients in 24-month follow-up, but after repeated procedure and circumferential PV isolation, the success rate increased to 59.6% in 16 ± 7 months follow-up. Conclusion
Ablation has become the standard treatment for paroxysmal AF. The European Society of Cardiology guidelines updated in 2012 recommend catheter ablation in symptomatic, recurrent, paroxysmal AF in patients who are suffering from arrhythmia despite taking AAD (IA) [46]. Catheter ablation should be also considered as first-line therapy in selected patients with symptomatic paroxysmal AF as an alternative to AAD considering patient choice, benefit and risk (IIa). It is a repeatable procedure with high success rate and low rate of complications, limited to 4.5% total and 1.7% major (stroke, cardiac tamponade, death) [47]. New methods and tools to make the AF ablation more successful, precise as well as safer and quicker are Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
constantly being developed. The ablation of persistent and long-standing AF remains the challenge.
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Expert commentary
AF ablation is definitely the most intensively developed field of electrophysiology. AF is already the most common arrhythmia and its incidence will increase each year as the world’s population gets older. The success rate of paroxysmal AF ablation in patients without additional diseases is high. Over the years, this procedure has become safer and more accessible due to duration reduction and development of novel devices. The guidelines recommend AF ablation in patients suffering from paroxysmal AF despite taking AAD (IA) or even as a first-line therapy in selected ones (IIA). The efficacy of persistent and long-standing AF ablation leaves much to be desired. The recurrence rate is still high and there is a need to develop new tools and methods to deal with these patients. Five-year view
Contemporary classic methods of paroxysmal AF ablation are successful and safe when performed by an experienced operator. However, it takes a significant amount of time to master it. Moreover, the procedure duration usually exceeds 2 h that further limits its accessibility. The ‘single-shot’ methods like balloon cryoablation, multi-ablation RF catheters and laser balloon ablation are the response to the need for easier and quicker methods of paroxysmal AF ablation. These tools are
Review
likely to be developed further in the forthcoming years as they provide wider access to the AF ablation for both patients and operators. The role of autonomic system in AF triggering and maintenance is known to a limited extent. The positive results of ganglia ablation and renal denervation procedures confirm that modulation of autonomic system is not to be neglected in future interventional treatment of AF. Substrate-based approach remains the hot topic in AF ablation as the results of persistent and long-standing AF are poor. Novel devices support the operators with computational tools to map the rotors and focal sources that drive AF. The preliminary results of CFAE and FIRM ablations were very promising and we hope that ongoing trials will confirm these methods as safe and efficient solutions for large number of patients with persistent and long-lasting AF. Financial & competing interests disclosure
K Kaczmarek has received a research grant from Biosense Webster and is on the advisory board for Boston Scientific. L Szumowski has received research grants from Biosense Webster, Biotronik and Medtronic. P Ptaszynski has received research grants from Biosense Webster and Medtronic, as well as a research fellowship from St Jude Medical. He is also on the advisory board for Biosense Webster. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.
Key issues • Atrial fibrillation (AF) is the most common sustained arrhythmia and a major cause of stroke. • Catheter ablation is a safe and efficient method of interventional treatment of AF. • Ablation of paroxysmal AF generally focuses on electrical isolation of pulmonary veins from left atrium. • New methods of ‘single-shot’ pulmonary veins isolation – balloon cryoablation, circular radiofrequency catheter, visually guided laser balloon ablation are promising and help to make the procedure more efficient, quicker and easier. • Robotic navigation systems provide better catheter stability and allow the physician to move away from x-ray source. • Ablation of autonomic ganglia of left atrium added to the pulmonary vein isolation increases the procedure efficacy. • Catheter ablation in persistent and long-standing AF is still not as effective as in the paroxysmal AF. • Complex fractioned electrograms ablation, ganglionated plexi ablation and focal impulse and rotor modulation are ‘gleam of hope’ for patients with persistent and long-standing AF. • The next few years will provide us with the results of many important trials that will define the direction of development of AF ablation techniques.
References 1.
2.
Camm AJ, Kirchhof P, Lip GY, et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369-429 Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation in adults. JAMA 2001;285:2370
informahealthcare.com
3.
4.
5.
Jais P, Haissaguerre M, Shah DC, et al. A focal source of atrial fibrillation treated by discrete radiofrequency ablation. Circulation 1997;95:572-6 Haissaguerre M, Jaı¨s P. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659-66 Haı¨ssaguerre M, Shah DC, Jaı¨s P, et al. Electrophysiological breakthroughs from the
left atrium to the pulmonary veins. Circulation 2000;102:2463-5 6.
Pappone C, Rosanio S, Oreto G, et al. Circumferential Radiofrequency Ablation of Pulmonary. Circulation 2000;102:2619-28
7.
Ouyang F, Ba¨nsch D, Ernst S, et al. Complete isolation of left atrium surrounding the pulmonary veins: new insights from the double-Lasso technique in paroxysmal atrial fibrillation. Circulation 2004;110:2090-6
601
Review 8.
Nademanee K, McKenzie J, Kosar E, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol 2004;43:2044-53
9.
Boersma LV, Wijffels MC, Oral H, et al. Pulmonary vein isolation by duty-cycled bipolar and unipolar radiofrequency energy with a multielectrode ablation catheter. Heart Rhythm 2008;5:1635-42
10.
11.
Downloaded by [National Taiwan University] at 08:06 01 July 2015
Zuchowski, Kaczmarek, Szumowski, Li & Ptaszynski
12.
13.
procedure cryoballoon ablation: a comparison between the first and second generation balloon. J Cardiovasc Electrophysiol 2014. [Epub ahead of print] 20.
21.
Shin DI, Kirmanoglou K, Eickholt C, et al. Initial results of using a novel irrigated multielectrode mapping and ablation catheter for pulmonary vein isolation. Heart Rhythm 2014;11:375-83 Dukkipati SR, Neuzil P, Kautzner J, et al. The durability of pulmonary vein isolation using the visually guided laser balloon catheter: multicenter results of pulmonary vein remapping studies. Heart Rhythm 2012;9:919-25
22.
Dukkipati SR, Kuck KH, Neuzil P, et al. Pulmonary vein isolation using a visually guided laser balloon catheter: the first 200-patient multicenter clinical experience. Circ Arrhythm Electrophysiol 2013;6: 467-72
23.
Demazumder D, Mirotznik MS, Schwartzman D. Biophysics of radiofrequency ablation using an irrigated electrode. J Interv Card Electrophysiol 2001;5:377-89
24.
De Filippo P, He DS, Brambilla R, et al. Clinical experience with a single catheter for mapping and ablation of pulmonary vein ostium. J Cardiovasc Electrophysiol 2009;20:367-73 Bulava A, Hanisˇ J, Sitek D, et al. Catheter ablation for paroxysmal atrial fibrillation: a randomized comparison between multielectrode catheter and point-by-point ablation. Pacing Clin Electrophysiol 2010;33:1039-46 Mulder AA, Wijffels MC, Wever EF, et al. Pulmonary vein anatomy and long-term outcome after multi-electrode pulmonary vein isolation with phased radiofrequency energy for paroxysmal atrial fibrillation. Europace 2011;13:1557-61 Gaita F, Leclercq JF, Schumacher B, et al. Incidence of silent cerebral thromboembolic lesions after atrial fibrillation ablation may change according to technology used: comparison of irrigated radiofrequency, multipolar nonirrigated catheter and cryoballoon. J Cardiovasc Electrophysiol 2011;22:961-8 Herrera Siklo´dy C, Deneke T, Hocini M, et al. Incidence of asymptomatic intracranial embolic events after pulmonary vein isolation: comparison of different atrial fibrillation ablation technologies in a multicenter study. J Am Coll Cardiol 2011;58:681-8
14.
Gerstenfeld EP, Dixit S, Callans D, et al. Utility of exit block for identifying electrical isolation of the pulmonary veins. J Cardiovasc Electrophysiol 2002;13:971-9
15.
Duytschaever M, De Meyer G, Acena M, et al. Lessons from dissociated pulmonary vein potentials: entry block implies exit block. Europace 2013;15:805-12
25.
Pokushalov E, Turov A, Shugayev P, et al. Catheter ablation of left atrial ganglionated plexi for atrial fibrillation. Asian Cardiovasc Thorac Ann 2008;16:194-201
16.
Packer DL, Kowal RC, Wheelan KR, et al. Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial. J Am Coll Cardiol 2013;61:1713-23
26.
Pappone C, Santinelli V, Manguso F, et al. Pulmonary vein denervation enhances long-term benefit after circumferential ablation for paroxysmal atrial fibrillation. Circulation 2004;109:327-34
27.
Katritsis DG, Giazitzoglou E, Zografos T, et al. Rapid pulmonary vein isolation combined with autonomic ganglia modification: a randomized study. Heart Rhythm 2011;8:672-8
28.
Pokushalov E, Romanov A, Corbucci G, et al. A randomized comparison of pulmonary vein isolation with versus without concomitant renal artery denervation in patients with refractory symptomatic atrial fibrillation and resistant hypertension. J Am Coll Cardiol 2012;60: 1163-70
17.
Chierchia GB, Di Giovanni G, Ciconte G, et al. Second-generation cryoballoon ablation for paroxysmal atrial fibrillation: 1-year follow-up. Europace 2014;16:639-44
18.
Fu¨rnkranz A, Bordignon S, Dugo D, et al. Improved 1-year clinical success rate of pulmonary vein isolation with the second-generation cryoballoon in patients with paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 2014. [Epub ahead of print]
19.
Giovanni G DI, Wauters K, Chierchia GB, et al. One-year follow-up after single
602
29.
Narayan SM, Krummen DE, Shivkumar K, et al. Treatment of atrial fibrillation by the ablation of localized sources: CONFIRM (Conventional Ablation for Atrial Fibrillation with or Without Focal Impulse and Rotor Modulation) trial. J Am Coll Cardiol 2012;60:628-36
30.
Pappone C, Vicedomini G, Manguso F, et al. Robotic magnetic navigation for atrial fibrillation ablation. J Am Coll Cardiol 2006;47:1390-400
31.
Shurrab M, Danon A, Lashevsky I, et al. Robotically assisted ablation of atrial fibrillation: a systematic review and meta-analysis. Int J Cardiol 2013;169: 157-65
32.
Bai R, DI Biase L, Valderrabano M, et al. Worldwide experience with the robotic navigation system in catheter ablation of atrial fibrillation: methodology, efficacy and safety. J Cardiovasc Electrophysiol 2012;23: 820-6
33.
Khan EM, Frumkin W, Ng GA, et al. First experience with a novel robotic remote catheter system: AmigoTM mapping trial. J Interv Card Electrophysiol 2013;37:121-9
34.
Sommer P, Richter S, Hindricks G, et al. Non-fluoroscopic catheter visualization using MediGuideTM technology: experience from the first 600 procedures. J Interv Card Electrophysiol 2014. [Epub ahead of print]
35.
Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report. Heart Rhythm 2012;9: 632-96.e21
36.
Noheria A, Kumar A, Wylie J V, et al. Catheter ablation vs antiarrhythmic drug therapy for atrial fibrillation: a systematic review. Arch Intern Med 2008;168:581-6
37.
Wilber DJ, Neuzil P, De Paola A, et al. Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial. JAMA 2010;303:333-40
38.
Jaı¨s P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation: the A4 study. Circulation 2008;118:2498-505
39.
Ouyang F, Tilz R, Chun J, et al. Long-term results of catheter ablation in paroxysmal atrial fibrillation: lessons from a 5-year follow-up. Circulation 2010;122:2368-77
Expert Rev. Med. Devices 11(6), (2014)
Interventional AF therapy
40.
Bertaglia E, Tondo C, De Simone A, et al. Does catheter ablation cure atrial fibrillation? Single-procedure outcome of drug-refractory atrial fibrillation ablation: a 6-year multicentre experience. Europace 2010;12:181-7
41.
Weerasooriya R, Khairy P, Litalien J, et al. Catheter ablation for atrial fibrillation: are results maintained at 5 years of follow-up? J Am Coll Cardiol 2011;57:160-6 Ganesan AN, Shipp NJ, Brooks AG, et al. Long-term outcomes of catheter ablation of atrial fibrillation: a systematic review and meta-analysis. J Am Heart Assoc 2013;2: e004549
Verma A, Mantovan R, Macle L, et al. Substrate and Trigger Ablation for Reduction of Atrial Fibrillation (STAR AF): a randomized, multicentre, international trial. Eur Heart J 2010;31:1344-56
44.
Verma A, Sanders P, Macle L, et al. Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II (STAR AF II): design and rationale. Am Heart J 2012(164):1-6.e6
45.
Pokushalov E, Romanov A, Artyomenko S, et al. Ganglionated plexi ablation for longstanding persistent atrial fibrillation. Europace 2010;12:342-6
46.
Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J 2012;33:2719-47
47.
Cappato R, Calkins H, Chen SA, et al. Updated worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circ Arrhythm Electrophysiol 2010;3:32-8
Downloaded by [National Taiwan University] at 08:06 01 July 2015
42.
43.
Review
informahealthcare.com
603
