Canadian Journal of Cardiology

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(2014) 1e8

Review

Atrial Fibrillation Therapies: Lest We Forget Surgery Hadi Daood Toeg, MD, MSc, Talal Al-Atassi, MD, MPH, and Buu-Khanh Lam, MD, MPH, FRCSC Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada

ABSTRACT

  RESUM E

Atrial fibrillation (AF) is a disease that causes a significant burden in a patient’s life. It is a known risk factor for heart failure, stroke, and premature death. The classic therapeutic strategies include rate control, rhythm control, and prevention of stroke. Pharmacological rhythm control with antiarrhythmic drugs can only be achieved 50% of the time while simultaneously subjecting patients to deleterious adverse reactions. With recent advances in catheter ablation procedures, rhythm control can be safely attained anywhere from 57%-80% of the time, depending on the number of repeat catheter ablation procedures that are performed and concomitant use of antiarrhythmic drugs. The Cox-Maze procedure is a technically challenging cut-and-sew atrial lesion set with associated morbidity, yet is still considered the gold standard for rhythm control. Fortunately, this procedure has been modified in efforts to improve the safety profile (shorter cross clamp and cardiopulmonary bypass time), to simplify lesion set creation with

La fibrillation auriculaire (FA) est une maladie qui entraîne un fardeau important dans la vie du patient. C’est un facteur de risque connu de re bral (AVC) et de l’insuffisance cardiaque, de l’accident vasculaire ce  pre mature e. Les strate gies the rapeutiques classiques la mortalite quence, la maîtrise du rythme et la incluent la maîtrise de la fre vention de l’AVC. La maîtrise pharmacologique du rythme à l’aide pre d’antiarythmisants peut seulement être obtenue dans 50 % du temps ment les patients à des effets inde sirables tout en exposant simultane  le tères. En raison des re centes avance es portant sur les ablations de ter, la maîtrise du rythme peut être atteinte de manière par cathe curitaire dans 57 % à 80 % du temps selon le nombre d’ablations se ter re pe  te es re alise es et l’utilisation concomitante des antipar cathe rie d’incisions dans arythmisants. L’intervention de Cox-Maze est une se les oreillettes selon une technique de « couper-coudre » complexe  associe e, mais qui est encore conside re e ayant une morbidite

Atrial fibrillation (AF) is the most common arrhythmia encountered by clinicians and it is estimated that 350,000 Canadians are living with AF.1 These numbers will only increase as the population continues to age and current therapy for chronic cardiovascular disease further improve patient survival.2 With a 60% increase in the number of admissions per year related to AF during the past 10 years, this condition creates a significant cost burden to the health care system ranging from 3 to 6 billion dollars per year in addition to the substantial mortality and morbidity from stroke, heart failure, and impaired quality of life associated with AF.3,4 Treatment options for this disease has historically been divided into 3 broad categories including rate control, rhythm control, and anticoagulation5; however, there is increased recognition that AF is a heterogeneous illness and that these treatment strategies must be tailored to individual idiosyncrasies, symptoms, and risks from stroke or bleeding.

This review will cover various up to date surgical interventions that are currently being used for the treatment of AF with the aim to raise awareness about these modalities among family physicians, cardiologists, and the general patient population.

Received for publication October 1, 2013. Accepted February 2, 2014. Corresponding author: Dr Buu-Khanh Lam, Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin St, Ottawa, Ontario K1Y 4W7, Canada. Tel.: þ1-613-761-5000; fax: þ1-613-761-5217. E-mail: [email protected] See page 6 for disclosure information.

Classification and Pathophysiology of AF The recommended AF classification scheme from the American and European cardiology societies emphasize temporal rhythm-based patterns of AF (Table 1).6 Understanding the various settings in which AF can occur will lead the clinician to a directed therapeutic approach based on the underlying etiology. These settings include: (1) concomitant AF that is associated with structural heart disease; (2) lone or isolated AF associated with no heart disease; and (3) postoperative AF associated with cardiothoracic surgery.6 The differential diagnosis when attributing a specific cause to AF is vast. AF can arise from noncardiac origins such as chronic lung disease, thyroid disease, electrolyte disturbances, alcohol consumption, and acute infections. In contrast, cardiac causes of AF include ischemic heart disease, rheumatic heart disease, valvular disease (mitral stenosis), hypertension, cardiomyopathies, heart failure, and pre-excitation syndromes.7 All of these conditions partially contribute to the development of AF by

0828-282X/$ - see front matter Ó 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cjca.2014.02.001

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Canadian Journal of Cardiology Volume - 2014

newer energy sources, and to perform this operation in a minimally invasive setting. Minimally invasive surgical AF ablation techniques have excellent safety profiles and can achieve rhythm control in up to 90% of patients. In contrast, patients undergoing open heart surgery can undergo either concomitant endocardial or epicardial AF ablation procedures without jeopardizing the surgery along with success rates from 60% to 88%. Thus, there has been an increase in current surgical options for treating AF because of novel approaches and energy sources which yield effective long-term results in patient care and minimize perioperative complications and thereby optimize the risk/ benefit ratio profile.

tant la technique ope ratoire de re  fe rence de la maîtrise du comme e  te  modifie e afin d’amrythme. Heureusement, cette intervention a e liorer le profil de se curite  (temps de clampage et de pontage care ation de la se rie diopulmonaire plus court), de simplifier la cre nergie et de re aliser cette d’incisions par de nouvelles sources d’e ration dans un cadre minimalement invasif. Les techniques chirope urgicales d’ablation de la FA minimalement invasives montrent curite  et peuvent atteindre une maîtrise du d’excellents profils de se rythme chez jusqu’à 90 % des patients. En revanche, les patients subissant la chirurgie à cœur ouvert peuvent subir soit l’ablation conpicardique sans comcomitante de la FA par voie endocardique ou e ussite allant de 60 % à promettre la chirurgie et avec des taux de re quent, les options chirurgicales actuelles de traite88 %. Par conse ment de la FA sont plus nombreuses, en raison des approches et des nergie nouvelles qui donnent des re sultats efficaces à long sources d’e terme dans les soins aux patients et minimisent les complications riope ratoires et, par conse quent, optimisent le profil du rapport pe risques-avantages.

increasing atrial pressure/dilatation, and atrial electrical activity, but the exact mechanisms are not clear.8,9

encumbrance of disease in patients with AF. Therefore, continuous implantable loop recording devices like the Reveal XT (Medtronic, Minneapolis, MN) should be considered to measure the burden of AF after catheter or surgical ablation because an implanted device can demonstrate recurrence of AF that other modalities like Holter monitoring would miss.14,15 This leads us to the clinical challenges that we face with medical treatment for AF: the risk of bleeding from anticoagulation, and intolerance or adverse events associated with AADs or rate-controlling drugs.

Medical Management To achieve and maintain normal sinus rhythm (NSR), chemical or electrical cardioversion may be performed with the latter option being more effective in persistent AF.10 The efficacy of different antiarrhythmic drugs (AADs) at restoring NSR are similar, with rates as high as 50% and possibly greater with repeated intermittent electrical cardioversions.11 However, the use of AADs increase the patient’s risk for drug-induced torsades de pointes which might be enhanced by QT prolongation, left ventricular dysfunction, hypokalemia, or hypomagnesemia, and sudden cardiac death without torsades.11,12 In contrast, amiodarone, the least proarrhythmic AAD, has serious extracardiac side effects like pulmonary fibrosis, hepatic and thyroid dysfunction when given chronically.13 Hence, the similar mortality incidence in rhythmcontrolled patients compared with rate-controlled patients might be credited to the adverse effects of AADs. Although most studies measure success of AF ablation using intermittent electrocardiogram (ECG) recordings (single ECG, Holter monitor), they do not capture the true Table 1. AF classification system based on either recurrence, self- or medication-mediated termination, or various causes of AF AF classification First detected Paroxysmal Persistent Permanent (long-standing persistent) Lone AF Concomitant AF Postoperative AF AF, atrial fibrillation.

Description        

First episode Self-terminates Recurring episodes Self-terminates < 7 days Recurring episodes Cardioversion needed to terminate < 7 days Continuous AF > 1 year Unsuccessful cardioversion, not indicated, or not attempted  Not associated with structural heart disease  Associated with structural heart disease or other general medical conditions  Occurring after cardiac surgical procedure

Anticoagulation and Left Atrial Appendage Management Arguably the most feared complication of AF is stroke. Two methods exist to prevent stroke in the context of AF: anticoagulation and left atrial (LA) appendage (LAA) closure. The 201016 and the focused 2012 update of the Canadian Cardiovascular Society (CCS) AF guidelines17 recommend first to assess the thromboembolic risk of the patient based on the Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack (CHADS2) score. The CHADS2 score is recommended over other scoring systems (Congestive Heart Failure, Hypertension, Age [75 years], Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age [65-74 years], Sex [Female]; CHA2DS2-VASc) because of its simplicity, extensive validation, and wide use.17 Anticoagulation, even with newer agents, exposes the patient to a tangible risk of bleeding.17 LAA closure can eliminate the need for anticoagulation in a select patient population and it can be performed percutaneously or surgically. In a contemporary trial, the WATCHMAN device (Atritech Inc, Plymouth, MN) was shown to be noninferior to warfarin at midterm outcomes.18 This is currently the only device undergoing US Food and Drug Administration approval. The CCS AF guidelines17 recommend the closure (excision or obliteration) of the LAA as part of AF ablation with mitral valve surgery (strong recommendation, low-quality evidence) and as part of AF ablation with aortic valve surgery or coronary bypass surgery if it does not increase the risk of surgery

Toeg et al. Surgery for Atrial Fibrillation

(conditional recommendation, low-quality evidence). If a surgical LAA closure is undertaken, it is paramount to ensure complete obliteration or removal to avoid remnant pockets that might still be a nidus for thrombosis, defeating the purpose of the procedure. Catheter-Based Management New nonpharmacological modalities have recently emerged as safe alternatives in restoring NSR. They are directed at eliminating potential local triggers and altering the electrophysiological connections of the heart. In patients with paroxysmal AF, the arrhythmogenic focus is commonly seen at the muscle sleeves of the pulmonary veins (PVs) or less commonly at other atrial sites including the superior vena cava, coronary sinus, LA posterior wall, interatrial septum, and the vein of Marshall.19 Current catheter ablation treatment uses radiofrequency (RF) energy that generates alternative electrical current that passes through myocardial tissue causing irreversible coagulation necrosis and leaves behind a nonconducting myocardial scar.20 Several randomized controlled trials (RCTs) have demonstrated superior results in restoring and maintaining NSR compared with AAD therapy, albeit most patients had paroxysmal AF and required multiple ablation procedures.21-25 A recent meta-analysis demonstrated that the single-procedure success rate of AAD therapy to achieve NSR was 57% (95% confidence interval [CI], 50-64%), and multiple ablations of AAD therapy improved this number to 71% (95% CI, 65-77%).25 Another metaanalysis grouped 7 RCTs comparing catheter ablation and medical treatment and found that 20% of ablated patients had recurrence of AF in contrast to 75% in those taking AADs. The relative risk reduction favoured ablation techniques with a value of 0.27 (95% CI, 0.18-0.41), however, there was significant heterogeneity with regard to catheter type and ablation procedure.26 In 2010, the European Society of Cardiology classified surgical ablation for AF as class B (level of evidence C) and is indicated only after failure of catheter ablation.27 A prospective RCT comparing minimally invasive surgical (MIS) ablation vs catheter ablation (longstanding persistent AF patients in whom AAD had failed and previous catheter ablation along with dilated atria and hypertension) demonstrated overall better freedom from AF at 12 months with 66% vs 37% (P ¼ 0.002), respectively.28 Although the surgical ablation group had more procedural adverse events (23% vs 3% in the catheter ablation group), most of these complications were minimal (pneumothorax, bleeding, pneumonia) and adverse event rates at 12 months became similar in both groups. Because this RCT used a more thorough 7-day Holter ECG recording that might have detected more events and that this patient population had more risk factors contributing to failure to maintain NSR (hypertension, LA dilatation, longstanding persistent AF), then it is not surprising to see a discrepancy in the expected freedom from AF percentages. Based on these findings and presenting clinical scenarios, patients might benefit more from consulting an arrhythmia team (electrophysiologist, cardiologist, and cardiac surgeon), one that would use the most successful, safe, and cost-effective method in treating AF. This multidisciplinary team would be involved in the preoperative

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decision-making to provide a patient-tailored approach, rather than a procedure-based approach, with the aim of improving patient outcomes. With the advent of hybrid procedures for AF ablation, the strengths of the surgical, minimally invasive, and percutaneous approaches can be combined, and minimize their individual weaknesses. For example, endocardial mapping of AF triggers and the addition of endocardial ablation lines might complement surgical ablation and lead to higher cure rates.29-31 Further research is needed to clarify the role of hybrid procedures in AF ablation which remains in its infancy. Surgical Management Cardiac surgeon, James Cox, devised the first effective surgical treatment for AF: a cut-and-sew technique, the Cox-Maze I, to create lines of scar designed to terminate macro-reentry circuits in the atria thereby preventing AF while preserving normal atrial kick.32 His model for paroxysmal AF entailed a premature PV trigger, or in < 10% automatic foci located elsewhere in the atria, that propagates to the LA and induces multiple macro-reentrant circuits involving both atria. In contrast, continuous AF is a selfperpetuating phenomenon likely due to atrial electrical remodelling and not necessarily anatomic remodelling.33 When atrial remodelling has occurred the initiating trigger or micro-reentrant circuit is no longer required. Thus, treatment of long-standing persistent AF focused on PV isolation is likely to fail. Because of the high incidence of postoperative heart block and technical operative difficulties, the original Cox-Maze procedure was modified 2 more times resulting in the Cox-Maze III (CM-III) procedure (Fig. 1). Despite the technically demanding procedure and operative mortality rate of 1.5%-3%, long-term results at 5 years demonstrated 96.6%-99% of patients free of AF.34,35 This technique is considered to be the gold standard for surgical treatment of AF. A major limitation in historical outcomes after surgical ablation is the method of monitoring AF recurrence: single ECGs and absence of symptoms would fail to reveal paroxysmal asymptomatic episodes and thus, overinflate the rate of freedom from AF. In efforts to simplify the cut-and-sew procedure further, Melby and colleagues devised similar ablation lesion sets with the use of alternative energy sources.36 This entailed omitting the atrial septal lesion in the previous CM-III version which was mostly used for exposing the LA, and performing an independent isolation of the PVs by a connecting lesion (Fig. 1). The new Cox-Maze IV procedure used bipolar RF energy or cryoenergy to create lesions with similar efficacy to the CM-III (91% free from AF after 6 months and 90% after 2 years) while having significantly shorter cross clamp times (Fig. 1B).36-38 Cox then devised a modified Cox-Maze, known as a mini-Maze procedure, that can be created with various forms of energy sources to achieve the minimum ablation lesion set required to isolate AF. These lesions included: (1) an incision encircling the PVs; (2) an LA isthmus and companion coronary sinus lesion; and (3) a right atrial isthmus lesion.33 The Achilles’ heel of the operation, as noted by Cox, is the incomplete ablation at the LA isthmus and the coronary sinus lesions.39 This rushed in a new era of less invasive, highly efficacious surgical techniques that could be used with concomitant open-heart surgery or without the use of cardiopulmonary bypass.

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using endocardial or epicardial ablation. Biatrial lesions sets, which include the CM-III and derivatives, are the most effective lesion set, reserved for patients with longstanding persistent, highly symptomatic AF, or young patients undergoing right heart surgery.40 The LA lesion set can be used in patients with recent onset paroxysmal AF or those undergoing other non-right heart surgery. New forms of energy sources such as microwave, laser, RF, high-intensity focused ultrasound, and cryoablation, have revolutionized the surgical treatment of AF especially when open-heart surgery is already scheduled; a summary of the most commonly used energy sources are found in Table 2. Some limitations of these energy sources compared with the traditional cut-and-sew technique is the uncertainty of creating transmural lesions; hence, laser, microwave and, to a lesser extent, high-frequency ultrasound energy sources have demonstrated less clinical efficacy.41,42 Alternatively, bipolar devices (jaw-clamp structure) can effectively achieve transmurality because the device can measure the amount of impedance as the atrial tissue is clamped and ablated. This begs the question, which energy source will provide the best results and minimize complications (Table 2)? In a recent systematic review, Basu and colleagues43 concluded that there is substantial evidence from randomized studies to suggest the superiority of bipolar RF ablation over microwave ablation; furthermore, bipolar RF ablation was recommended by these authors because it achieves transmurality more often and tends to have a shorter procedural time when compared with unipolar RF ablation (Table 2).44

Figure 1. The various forms of Cox-Maze lesion sets performed on the LA and RA. (A) CM-III biatrial lesion sets include biauricular resection, denoted by solid red lines, circumferential PV lesion along with connecting lesions to the LAA, interatrial septum, and the MV isthmus. (B) The CM-IV lesions are created in a similar fashion with the exception of the interatrial septum connecting lesion, RAA resection, and an additional lesion is made from the RAA to the TV annulus. The blue dotted line denotes isolated left and right PV lesion sets along with a connecting line between the 2 circular lesions. CM-III, Cox-Maze procedure third revision; CM-IV, Cox-Maze procedure fourth revision; CS, coronary sinus; IVC, inferior vena cava; LA, left atrium; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; LV, left ventricle; MV, mitral valve; PV, pulmonary vein; RA, right atrium; RAA, right atrial appendage; RIPV, right inferior PV; RSPV, right superior PV; SVC, superior vena cava; TV, tricuspid valve.

The modern cardiac surgeon currently has an arsenal of different energy sources to achieve transmural ablation lesions along with a choice of lesion sets. These alternative energy sources reduce surgical time, help achieve transmurality, maintain endothelial integrity, lessen bleeding, facilitate a minimally invasive approach, and eliminate the technical challenges associated with the cut-and-sew Cox-Maze procedure. Three broad lesion set categories exist in the surgical treatment of AF: (1) PV isolation; (2) LA lesion set; or (3) biatrial lesion set. Each lesion set should be tailored to the clinical setting; for example, new-onset paroxysmal AF patients would likely benefit from a PV isolation lesion set either

MIS Ablation Off-pump MIS ablation and LA appendage excision procedures have been performed since the mid-2000s.45,46 These surgeries require general anesthetics, two 10-mm thoracic ports, one 5-cm working port (non-rib spreading) unilaterally or bilaterally, and a video-assisted thoracoscope (Fig. 2). Although other groups have used microwave, unipolar RF ablation, cryothermy, and high-intensity focused ultrasound as their energy source,45,47-49 most groups have used bipolar RF ablation for creating pulmonary vein isolation lesions (with or without ganglionic plexus ablation, division of the ligament of Marshall, and LAA excision) and have demonstrated 75%-90% freedom from AF (62% in long-standing persistent),50 albeit outcome measurement (freedom from AF) varied with either 24- to 48-hour Holter monitor or 1430 day continuous monitoring.45,51-53 The overall procedural success rate was 99.5% (defined as completion of the planned procedure without conversion to a median sternotomy or cardiopulmonary bypass) as demonstrated in a recent review that investigated thoracoscopic bipolar RF ablation.50 Furthermore, Beyer and colleagues performed minimally invasive bipolar RF ablation with bilateral pulmonary vein isolation, autonomic denervation (via a pacing/sensing ablation pen/probe), and LAA resection on 100 patients in whom either AAD or catheter ablation therapy had failed.54 The overall conversion and maintenance of NSR was 87% (measured using 24-hour Holter monitor) with a further AF subtype breakdown as follows: paroxysmal, 93%; persistent, 96%; and long-standing persistent, 71% (Table 3). Although the overall complication rate approached 14%, there were no

Toeg et al. Surgery for Atrial Fibrillation

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Table 2. Summary of commonly used energy sources for surgical ablation Energy source

Advantages

Unipolar RF

 Variety of probes available

Bipolar RF

        

Microwave HIFU Cryoablation

Disadvantages

Safe, efficient method (more efficient than unipolar) Real-time assessment of transmural lesions Lower risk of thromboembolism Efficient method Quick application Satisfactory transmural lesions Good safety record Smooth well demarcated transmural lesions (low risk of bleeding/perforation) Less endocardial thrombus formation

           

Less efficient More thrombogenic Atrioesophageal fistula (rare) More thrombogenic Pulmonary vein stenosis (rare) Marginal transmural lesion creation Risk of perforation (higher energy) Risk of collateral tissue damage Limited to epicardial application Rigid probes (less flexibility) Limited to endocardial ablation Coronary artery stenosis (rare)

HIFU, high-intensity focused ultrasound; RF, radiofrequency.

significant irreversible adverse events such as death or stroke.54 As mentioned previously, the RCT that compared MIS ablation vs catheter ablation demonstrated overall better freedom from AF at 12 months; however, the surgical ablation group had significantly more procedural-related adverse events (23% vs 3% in the catheter ablation group; P ¼ 0.001), most of which included pneumothorax, bleeding, and pneumonia.28 Recent trends and outcomes from the Society of Thoracic Surgeons (STS) database (2005-2010) regarding stand-alone surgical ablation (via MIS or sternotomy) have demonstrated a safe complication rate of 0.7% for mortality or stroke, a rate of 1% for pacemaker, and a median length of

hospital stay of 4 days.55 It is also important to note that offpump MIS ablation was only introduced recently; therefore, the surgical learning curve should be considered. Thus, although MIS for AF ablation is effective in restoring and maintaining NSR, abating symptoms, and discontinuing anticoagulation therapy, adverse events such as hemo/pneumothorax, phrenic nerve injury, and need for pacemaker must be taken into account.54 Concomitant Surgical Intervention Preoperative AF of any type in patients undergoing open heart surgery are at increased risk of late morbidity, stroke, congestive heart failure, and perioperative and late mortality when compared with case-matched patients in NSR.56-58 Several cardiovascular societies’ expert consensus panels including the European Heart Rhythm Association (Heart Rhythm Society), the Society of Thoracic Surgeons, and the International Society of Minimally Invasive Cardiothoracic Surgery recommend that all patients with preoperative AF should be considered for surgical ablation weighing the risks and benefits of whether adding this procedure is small when performed by an experienced surgeon, or adequate probability of success.59,60 The main energy sources used are similar to what is used in minimally invasive AF ablation procedures. Although bipolar RF epicardial lesions can be achieved with an off-pump technique, cryothermal energy-mediated epicardial lesion creation requires an arrested emptied heart because the heat sink effect makes it difficult to achieve transmural lesions from the epicardial surface of a full heart.61 Consequently, concomitant cardiac surgical procedures using a cryoablation method can yield excellent results as Table 3. Summary of various contemporary AF treatment strategies for rhythm control Intervention

Figure 2. Drawing of a patient demonstrating small port hole incisions (10 mm) that are created in the anterior thorax for surgical and video instruments and a slightly larger working port (50 mm) is created just under the breast. These incisions can be made either unilaterally or bilaterally depending on the planned procedure.

AAD Single CA and AAD Multiple CAs Multiple CAs and AAD Concomitant SA and AAD MIS-SA CM-III and CM-IV

Success rate

References

50% 57% 70% 77% 60-88% 75-90% 91%

11-13 25 21-25 21-25 60-65 45,51-54 36-38

AAD, antiarrhythmic drug; AF, atrial fibrillation; CA, catheter ablation; CM, Cox-Maze; MIS, minimally invasive surgery; SA, surgical ablation.

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demonstrated by Mack and colleagues with an 88.5% rate of freedom from AF after 1 year.62 Several surgical ablation RCTs have also demonstrated successful restoration and maintenance of NSR with concomitant mitral valve surgery. Abreu and colleagues showed that 79.4% of patients who underwent concomitant AF ablation were in NSR and only 26.9% of mitral valve surgical patients without ablation were in NSR (P ¼ 0.001).63 Von Oppell’s and Chevalier’s groups also showed that AF ablation patients undergoing mitral valve surgery were significantly more in NSR at 75% and 57%, respectively.64,65 Similarly, patients undergoing non-mitral valve surgery such as coronary artery bypass or aortic valve surgery who underwent concomitant AF ablation demonstrated NSR rates of 79%.66 Even though preoperative AF is associated with increased risk for morbidity and mortality (more so in patients with normal left ventricular function), less than 40% of patients with AF undergoing cardiac surgery had concomitant surgical ablation. Furthermore, long-term clinical outcomes after surgical ablation in the literature are insufficiently reported with some groups demonstrating slightly improved survival compared with nonablated AF patients (74.4% vs 69.7%, respectively; P ¼ 0.34). Overall, rates of NSR success ranges from 57% to 88% in concomitant open heart surgical patients measured mostly using 48-hour Holter monitor (Table 3). The variability of these results is likely explained by the different ablation lesion sets, type of energy source used, and the patient’s AF subtype. The safety profile of adding AF ablation lesion sets while performing other open heart surgical procedures is excellent, with no significant differences in death, repeat surgery, renal injury, prolonged intensive care unit stay, or prolonged ventilation.67 Conclusions AF is a complex pathophysiological process compounded by patients’ comorbidities, and local environment: it is a serious disease that causes a significant burden in a patient’s life. It is a known risk factor for heart failure, stroke, and mortality. Medical therapy and catheter ablation have known benefits and limitations.19,26,60,68 The original, efficacious Cox-Maze procedure has been modified over recent years in an effort to: (1) improve the safety profile; (2) simplify lesion creation with newer energy sources; and (3) be transferable to a minimally invasive platform.33,35-39 With this evolution, we have developed MIS ablation techniques for the sole purpose of AF ablation with good safety profiles and efficacy (rhythm control from 75% to 90%) (Table 3).10,49-54 Similar to the 2011 CCS guidelines,69 we recommend patients with refractory AF, despite optimal medical and catheter-based interventions, to undergo MIS ablation (pulmonary vein isolation and autonomic plexus denervation and LAA excision) in experienced centres with low adverse event rates. Furthermore, we recommend concomitant AF ablation (epicardial or endocardial ablation lesion creation dependent on type of cardiac surgery) in selected AF patients undergoing open heart surgery in experienced centres, because freedom from AF and oral anticoagulation has demonstrated moderate results of 60%-88% (Table 3).62-66,69 Finally, current surgical options in the treatment of AF are expanding because novel approaches and technologies have

Canadian Journal of Cardiology Volume - 2014

yielded effective midterm results and have limited risk to our patients. Lest we forget, surgical ablation of AF, whether concomitant, via MIS techniques or in a hybrid context, will always be an integral part of the armamentarium of the arrhythmia team treating AF patients. Disclosures The authors have no conflicts of interest to disclose. References 1. Humphries KH, Jackevicius C, Gong Y, et al. Population rates of hospitalization for atrial fibrillation/flutter in Canada. Can J Cardiol 2004;20:869-76. 2. Miyasaka Y, Barnes ME, Gersh BJ, et al. Secular trends in incidence of atrial fibrillation in Olmsted County, Minnesota, 1980 to 2000, and implications on the projections for future prevalence. Circulation 2006;114:119-25. 3. Wodchis WP, Bhatia RS, Leblanc K, Meshkat N, Morra D. A review of the cost of atrial fibrillation. Value Health 2012;15:240-8. 4. Heeringa J, van der Kuip DA, Hofman A, et al. Prevalence, incidence and lifetime risk of atrial fibrillation: the Rotterdam study. Eur Heart J 2006;27:949-53. 5. Dewland TA, Marcus GM. Rate vs rhythm control in atrial fibrillation: can observational data trump randomized trial results? Arch Int Med 2012;172:983-4. 6. Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation-executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J 2006;27:1979-2030. 7. Kannel WB, Wolf PA, Benjamin EJ, Levy D. Prevalence, incidence, prognosis, and predisposing conditions for atrial fibrillation:populationbased estimates. Am J Cardiol 1998;82:2N-9N. 8. Everett TH 4th, Olgin JE. Basic mechanisms of atrial fibrillation. Cardiol Clin 2004;22:9-20. 9. Nattel S, Li D, Yue L. Basic mechanisms of atrial fibrillation-very new insights into very old ideas. Annu Rev Physiol 2000;62:51-77. 10. Watson T, Shanstila E, Lip GY. Modern management of atrial fibrillation. Clin Med 2007;7:28-34. 11. Crijns HJ, Van Gelder IC, Van Gilst WH, et al. Serial antiarrhythmic drug treatment to maintain sinus rhythm after electrical cardioversion for chronic atrial fibrillation or atrial flutter. Am J Cardiol 1991;68:335-41. 12. Kurita T, Motoki K, Yasuoka R, et al. Rhythm control should be better for the management of patients with atrial fibrillation and heart failureerhythm control vs. rate control: which is better in the management of atrial fibrillation? (Rhythm-side). Circ J 2011;75:979-85. 13. Goldschlager N, Epstein AE, Naccarelli G, Olshansky B, Singh B. Practical guidelines for clinicians who treat patients with amiodarone. Practice Guidelines Subcommittee, North American Society of Pacing and Electrophysiology. Arch Int Med 2000;160:1741-8. 14. Botto GL, Padeletti L, Santini M, et al. Presence and duration of atrial fibrillation detected by continuous monitoring: crucial implications for the risk of thromboembolic events. J Cardiovasc Electrophysiol 2009;20: 241-8.

Toeg et al. Surgery for Atrial Fibrillation 15. Martinek M, Aichinger J, Nesser HJ, Ziegler PD, Purerfellner H. New insights into long-term follow-up of atrial fibrillation ablation: full disclosure by an implantable pacemaker device. J Cardiovasc Electrophysiol 2007;18:818-23. 16. Cairns JA, Connolly S, McMurtry S, et al. Canadian Cardiovascular Society atrial fibrillation guidelines 2010: prevention of stroke and systemic thromboembolism in atrial fibrillation and flutter. Can J Cardiol 2011;27:74-90. 17. Skanes AC, Healey JS, Cairns JA, et al. Focused 2012 update of the Canadian Cardiovascular Society atrial fibrillation guidelines: recommendations for stroke prevention and rate/rhythm control. Can J Cardiol 2012;28:125-36. 18. Reddy VY, Doshi SK, Sievert H, et al. Percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation: 2.3-year follow-up of the PROTECT AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients with Atrial Fibrillation) Trial. Circulation 2013;127:720-9. 19. Oral H, Knight BP, Tada H, et al. Pulmonary vein isolation for paroxysmal and persistent atrial fibrillation. Circulation 2002;105:1077-81. 20. Haines DE. The biophysics of radiofrequency catheter ablation in the heart: the importance of temperature monitoring. Pacing Clin Electrophysiol 1993;16:586-91. 21. Wilber DJ, Pappone C, Neuzil P, 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. 22. Khaykin Y, Skanes A, Champagne J, et al. A randomized controlled trial of the efficacy and safety of electroanatomic circumferential pulmonary vein ablation supplemented by ablation of complex fractionated atrial electrograms versus potential-guided pulmonary vein antrum isolation guided by intracardiac ultrasound. Circ Arrhythm Electrophysiol 2009;2: 481-7. 23. Pappone C, Augello G, Sala S, et al. A randomized trial of circumferential pulmonary vein ablation versus antiarrhythmic drug therapy in paroxysmal atrial fibrillation: the APAF Study. J Am Coll Cardiol 2006;48: 2340-7. 24. Jais P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation: the A4 study. Circulation 2008;118: 2498-505. 25. Parkash R, Tang AS, Sapp JL, Wells G. Approach to the catheter ablation technique of paroxysmal and persistent atrial fibrillation: a meta-analysis of the randomized controlled trials. J Cardiovasc Electrophysiol 2011;22: 729-38. 26. Chen HS, Wen JM, Wu SN, Liu JP. Catheter ablation for paroxysmal and persistent atrial fibrillation. Cochrane Database Syst Rev 2012;4: CD007101. 27. European Heart Rhythm Association, European Association for CardioThoracic Surgery, Camm AJ, 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) [erratum in 2011;32: 1172]. Eur Heart J 2010;31:2369-429. 28. Boersma LV, Castella M, van Boven W, et al. Atrial fibrillation catheter ablation versus surgical ablation treatment (FAST): a 2-center randomized clinical trial. Circulation 2012;125:23-30. 29. La Meir M, Gelsomino S, Luca F, et al. Minimally invasive surgical treatment of lone atrial fibrillation: early results of hybrid versus standard minimally invasive approach employing radiofrequency sources. Int J Cardiol 2013;167:1469-75.

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30. Gelsomino S, Van Breugel HN, Pison L, et al. Hybrid thoracoscopic and transvenous catheter ablation of atrial fibrillation. Eur J Cardiothorac Surg 2014:401-7. 31. Muneretto C, Bisleri G, Bontempi L, Curnis A. Durable staged hybrid ablation with thoracoscopic and percutaneous approach for treatment of long-standing atrial fibrillation: a 30-month assessment with continuous monitoring. J Thorac Cardiovasc Surg 2012;144:1460-5 [discussion: 5]. 32. Cox JL, Schuessler RB, D’Agostino HJ Jr, et al. The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure. J Thorac Cardiovasc Surg 1991;101:569-83. 33. Cox JL. Surgical treatment of atrial fibrillation: a review. Europace 2004;5(suppl 1):S20-9. 34. Prasad SM, Maniar HS, Camillo CJ, et al. The Cox maze III procedure for atrial fibrillation: long-term efficacy in patients undergoing lone versus concomitant procedures. J Thorac Cardiovasc Surg 2003;126:1822-8. 35. Cox JL, Ad N, Palazzo T, et al. Current status of the Maze procedure for the treatment of atrial fibrillation. Semin Thorac Cardiovasc Surg 2000;12:15-9. 36. Melby SJ, Zierer A, Bailey MS, et al. A new era in the surgical treatment of atrial fibrillation: the impact of ablation technology and lesion set on procedural efficacy. Ann Surg 2006;244:583-92. 37. Chiappini B, Martin-Suarez S, LoForte A, et al. Cox/Maze III operation versus radiofrequency ablation for the surgical treatment of atrial fibrillation: a comparative study. Ann Thorac Surg 2004;77:87-92. 38. Weimar T, Schena S, Bailey MS, et al. The Cox-Maze procedure for lone atrial fibrillation: a single-center experience over 2 decades. Circ Arrhythm Electrophysiol 2012;5:8-14. 39. Cui YQ, Sun LB, Li Y, et al. Intraoperative modified Cox mini-Maze procedure for long-standing persistent atrial fibrillation. Ann Thorac Surg 2008;85:1283-9. 40. McCarthy PM, Kruse J, Shalli S, et al. Where does atrial fibrillation surgery fail? Implications for increasing effectiveness of ablation. J Thorac Cardiovasc Surg 2010;139:860-7. 41. Neven K, Schmidt B, Metzner A, et al. Fatal end of a safety algorithm for pulmonary vein isolation with use of high-intensity focused ultrasound. Circ Arrhythm Electrophysiol 2010;3:260-5. 42. Pruitt JC, Lazzara RR, Ebra G. Minimally invasive surgical ablation of atrial fibrillation: the thoracoscopic box lesion approach. J Interv Card Electrophysiol 2007;20:83-7. 43. Basu S, Nagendran M, Maruthappu M. How effective is bipolar radiofrequency ablation for atrial fibrillation during concomitant cardiac surgery? Interact Cardiovasc Thorac Surg 2012;15:741-8. 44. Bugge E, Nicholson IA, Thomas SP. Comparison of bipolar and unipolar radiofrequency ablation in an in vivo experimental model. Eur J Cardiothorac Surg 2005;28:76-80 [discussion: 2]. 45. Wolf RK, Schneeberger EW, Osterday R, et al. Video-assisted bilateral pulmonary vein isolation and left atrial appendage exclusion for atrial fibrillation. J Thorac Cardiovasc Surg 2005;130:797-802. 46. Edgerton JR, Jackman WM, Mack MJ. Minimally invasive pulmonary vein isolation and partial autonomic denervation for surgical treatment of atrial fibrillation. J Interv Card Electrophysiol 2007;20:89-93. 47. Salenger R, Lahey SJ, Saltman AE. The completely endoscopic treatment of atrial fibrillation: report on the first 14 patients with early results. Heart Surg Forum 2004;7:E555-8. 48. Klinkenberg TJ, Ahmed S, Ten Hagen A, et al. Feasibility and outcome of epicardial pulmonary vein isolation for lone atrial fibrillation using

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Canadian Journal of Cardiology Volume - 2014 minimal invasive surgery and high intensity focused ultrasound. Europace 2009;11:1624-31.

Minimally Invasive Cardiothoracic Surgery (ISMICS) 2009. Innovations (Phila) 2010;5:74-83.

49. Nasso G, Bonifazi R, Del Prete A, et al. Long-term results of ablation for isolated atrial fibrillation through a right minithoracotomy: toward a rational revision of treatment protocols. J Thorac Cardiovasc Surg 2011;142:e41-6.

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50. Mack MJ. Current results of minimally invasive surgical ablation for isolated atrial fibrillation. Heart Rhythm 2009;6:S46-9. 51. Edgerton JR, Edgerton ZJ, Weaver T, et al. Minimally invasive pulmonary vein isolation and partial autonomic denervation for surgical treatment of atrial fibrillation. Ann Thorac Surg 2008;86:35-8 [discussion: 9]. 52. Edgerton JR, McClelland JH, Duke D, et al. Minimally invasive surgical ablation of atrial fibrillation: six-month results. J Thorac Cardiovasc Surg 2009;138:109-13 [discussion: 14]. 53. McClelland JH, Duke D, Reddy R. Preliminary results of a limited thoracotomy: new approach to treat atrial fibrillation. J Cardiovasc Electrophysiol 2007;18:1289-95. 54. Beyer E, Lee R, Lam BK. Point: minimally invasive bipolar radiofrequency ablation of lone atrial fibrillation: early multicenter results. J Thorac Cardiovasc Surg 2009;137:521-6. 55. Ad N, Suri RM, Gammie JS, et al. Surgical ablation of atrial fibrillation trends and outcomes in North America. J Thorac Cardiovasc Surg 2012;144:1051-60. 56. Quader MA, McCarthy PM, Gillinov AM, et al. Does preoperative atrial fibrillation reduce survival after coronary artery bypass grafting? Ann Thorac Surg 2004;77:1514-22 [discussion: 22-4]. 57. Ngaage DL, Schaff HV, Barnes SA, et al. Prognostic implications of preoperative atrial fibrillation in patients undergoing aortic valve replacement: is there an argument for concomitant arrhythmia surgery? Ann Thorac Surg 2006;82:1392-9. 58. Ngaage DL, Schaff HV, Mullany CJ, et al. Influence of preoperative atrial fibrillation on late results of mitral repair: is concomitant ablation justified? Ann Thorac Surg 2007;84:434-42 [discussion: 42-3]. 59. Ad N, Cheng DC, Martin J, et al. Surgical ablation for atrial fibrillation in cardiac surgery: a consensus statement of the International Society of

61. Lee R, Kruse J, McCarthy PM. Surgery for atrial fibrillation. Nat Rev Cardiol 2009;6:505-13. 62. Mack CA, Milla F, Ko W, et al. Surgical treatment of atrial fibrillation using argon-based cryoablation during concomitant cardiac procedures. Circulation 2005;112:I1-6. 63. Abreu Filho CA, Lisboa LA, Dallan LA, et al. Effectiveness of the Maze procedure using cooled-tip radiofrequency ablation in patients with permanent atrial fibrillation and rheumatic mitral valve disease. Circulation 2005;112:I20-5. 64. von Oppell UO, Masani N, O’Callaghan P, et al. Mitral valve surgery plus concomitant atrial fibrillation ablation is superior to mitral valve surgery alone with an intensive rhythm control strategy. Eur J Cardiothorac Surg 2009;35:641-50. 65. Chevalier P, Leizorovicz A, Maureira P, et al. Left atrial radiofrequency ablation during mitral valve surgery: a prospective randomized multicentre study (SAFIR). Arch Cardiovasc Dis 2009;102:769-75. 66. Khargi K, Lemke B, Deneke T. Concomitant anti-arrhythmic procedures to treat permanent atrial fibrillation in CABG and AVR patients are as effective as in mitral valve patients. Eur J Cardiothorac Surg 2005;27: 841-6. 67. Gammie JS, Haddad M, Milford-Beland S, et al. Atrial fibrillation correction surgery: lessons from the Society of Thoracic Surgeons National Cardiac Database. Ann Thorac Surg 2008;85:909-14. 68. Oral H, Scharf C, Chugh A, et al. Catheter ablation for paroxysmal atrial fibrillation: segmental pulmonary vein ostial ablation versus left atrial ablation. Circulation 2003;108:2355-60. 69. Page P, CCS Atrial Fibrillation Guidelines Committee. Canadian Cardiovascular Society atrial fibrillation guidelines 2010: surgical therapy. Can J Cardiol 2011;27:67-73.