Original Article
Radiofrequency ablation of atrial fibrillation during mitral valve surgery
Asian Cardiovascular & Thoracic Annals 2014, Vol. 22(7) 807–810 ß The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492313519990 aan.sagepub.com
Farouk Oueida1, Mohamed Ahmed Elawady2 and Khalid Eskander1
Abstract Objectives: Atrial fibrillation is the most common form of arrhythmia in mitral valve disease. Radiofrequency ablation is most commonly used for atrial fibrillation ablation during mitral valve surgery. Methods: This prospective study evaluated the midterm outcomes of intraoperative radiofrequency atrial fibrillation ablation during mitral valve surgery. Results: 52 patients were eligible for the study. Fifteen (28.8%) had a transseptal approach and 37 had a left atriotomy. Mitral valve replacement was performed in 16 patients, mitral valve repair in 31, and tricuspid repair in 8. Mean crossclamp time was 58.14. 20.08 min, and mean cardiopulmonary bypass time was 71.28 20.31 min. The mean ablation time was 6.41 0.21 min. There was no postoperative mortality. Sinus rhythm was documented in 44 (84.6%) patients on discharge, and 8 (15.4%) were discharged with atrial fibrillation; 2 of them returned to sinus rhythm after 3 months. After 12 months of follow-up, 46 (88.5%) patients were in sinus rhythm. Conclusion: Left atrial monopolar radiofrequency ablation during mitral valve surgery is a safe procedure with a high success rate.
Keywords Anti-arrhythmia agents, atrial fibrillation, catheter ablation, heart atria, heart valve prosthesis implantation, mitral valve
Introduction Atrial fibrillation (AF) is the most common form of arrhythmia in mitral valve disease, with incidence ranging from 30% to 84%.1 AF may cause heart failure and thromboembolic complications, leading to increased morbidity and mortality, with a high financial burden. Medical treatment in persistent AF is not the best option due to high failure rates of up to 84%.2 The Cox maze operation with its modifications is the gold standard for surgical treatment of AF, with nearly 100% success rates, but it is a complex procedure needing surgical experience. The Cox maze also requires a long crossclamp time and there is a higher incidence of bleeding.3,4 This has led to the evolution of less invasive surgical techniques with the same surgical concepts as the Cox maze procedure but replacing the scissors in the cut-and-sew method by power sources to create the lines of conduction block without cutting the tissue. These include radiofrequency (RF), microwave, laser, high-frequency focused ultrasound, and cryoablation.5
Since the year 2000, RF has been one of the most commonly used methods for ablation.5,6 The aim of this study was to evaluate the midterm results of left atrial monopolar RF ablation for persistent AF during mitral valve surgery.
Patients and methods A prospective study was undertaken to evaluate the midterm results of intraoperative radiofrequency ablation during mitral valve operations in Saud Al Babtain 1 Cardiac Surgery Department, Saud Al-Babtain Cardiac Centre, Dammam, Saudi Arabia 2 Cardiothoracic Surgery Department, Banha Faculty of Medicine, Banha University, Egypt
Corresponding author: Mohamed Ahmed Elawady, MD, Cardiothoracic Surgery Department, Banha Faculty of Medicine, Banha University, Banha 2344, Egypt. Email: [email protected]
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
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Asian Cardiovascular & Thoracic Annals 22(7)
Cardiac Center, Dammam, Saudi Arabia. After approval by the institutional ethics and research committee, all patients provided signed consent for surgery including the ablation procedure. Inclusion criteria were elective mitral valve surgery, left ventricular ejection fraction 535%, and persistent preoperative AF. Exclusion criteria were: age >70 years; chronic obstructive pulmonary disease; poor left ventricular function (ejection fraction 40-years old or with history of ischemic heart disease. All patients were anesthetized with propofol and fentanyl, using a target-controlled intravenous anesthesia protocol. Each patient had a central venous catheter and Swan-Ganz catheter with invasive monitoring of blood pressure. All patients had transesophageal echocardiography pre-bypass and immediately after weaning from cardiopulmonary bypass. Patients had either a median sternotomy or a limited right anterior
thoracotomy. All operations were performed using a conventional cardiopulmonary bypass machine with crossclamping of the aorta and cardioplegia. Cardiopulmonary bypass was conducted using a membrane oxygenator and moderate hypothermia. The mitral valve was approached by either a left or right atriotomy using a transseptal approach. RF ablation was performed under crossclamping after mitral valve repair or replacement. RF ablation was undertaken using a Medtronic Cardioblate 68000 Surgical Ablation System Generator Device and a model 60813 Standard Cardioblate Surgical Ablation Pen. The generator power was set at 30 W, and lesions were produced at a temperature of 70 C–80 C. Linear lesions in the left atrium were produced according to the scheme presented in Figure 1. Each 1-cm long segment of the ablation line was created by dragging the distal tip of the Cardioblate pen gently across the endocardial tissue under the surgeon’s vision, moving in an oscillating motion at 1 cms 1 for approximately 20 s until the targeted endocardium became pale. The first ablation line was created around the right and left pulmonary veins. One lesion connected the left lower pulmonary vein with the mitral annulus at the base of the posterior leaflet. The left atrial appendage was sewn in all patients. Two pacemaker wires were placed: one in the right atrium and the second in the ventricle; they were cut before patients were discharged home. Oral anticoagulation was administered to all patients. They were started on subcutaneous lowmolecular-weight heparin until the target international normalized ratio was reached. Oral anticoagulants were discontinued after the 3rd month in mitral valve repair cases with sinus rhythm. According to our protocol, all patients had an intraoperative amiodarone infusion with a loading dose of 300 mg followed by continuous infusion of a total of 1200 mg over the next 24 h. Amiodarone was administered orally for 3 months
Table 1. Preoperative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Mean age (years) Male Female Ejection fraction Mean PA pressure (mm Hg) Mean left atrial size (cm)
43.22 6.23 31 (59.6%) 21 (40.4%) 51.46% 6.59% 47.5 11.4 5.77 0.68
PA: pulmonary artery.
Figure 1. Scheme of ablation. Note: the left atrial appendage is sewn.
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
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after discharge. All patients underwent transthoracic echocardiography before discharge, and a 12-lead ECG and transthoracic echocardiography at 1, 3, 6, and 12 months during outpatient visits. All demographic data, preoperative, operative, and postoperative data were collected, and statistical analysis was conducted using SPSS version 18.0 software (SPSS, Inc., Chicago, IL, USA). Values of continuous variables are expressed as mean standard deviation. Categorical variables are expressed as numbers and percentages.
Results Eight (15.4%) patients had a small right anterior thoracotomy approach, and 44 (84.6%) had a midline sternotomy. In 15 (28.8%) patients, the transseptal approach was used, the other 37 had a left atriotomy. Two (3.8%) patients had a left atrial thrombus. The left atrial appendage was closed in all patients. Mitral valve replacement was performed in 21 (40.4%) patients, and 31 (59.6%) had mitral valve repair. Table 2 summarizes the surgical data. Intraoperatively, 41 patients had sinus rhythm immediately, and 3 returned to sinus rhythm after electrical cardioversion. Thus on arrival at the intensive care unit, 44 patients had sinus rhythm; 6 of them had one or more attack of AF during hospital stay but returned to sinus rhythm pharmacologically with no need for electrical cardioversion. No patient required permanent pacemaker implantation before discharge. Sinus rhythm was documented in 44 (84.6%) patients on discharge, and 8 (15.4%) were discharged with AF. One patient was reexplored for bleeding. The postoperative data are summarized in Table 3. Superficial sternal wound infection was found in one (1.9%) patient. There was no hospital mortality. Mean left atrial size before discharge was 5.43 cm in patients with sinus rhythm, and 6.13 cm in those with persistent AF. Of the 8 patients discharged in AF,
Table 2. Operative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Mitral valve repair Mitral valve replacement Mechanical valve Tissue valve Tricuspid valve repair Cardiopulmonary bypass time (min) Crossclamp time (min) Ablation time (min)
31 21 6 15 8 71.28 20.31 53.14 17.08 6.41 0.21
2 retuned to sinus rhythm after 3 months. At the 6- and 12-month follow-up, the total number in sinus rhythm was unchanged at 46, giving a total success rate of 88.46%.
Discussion Persistent postoperative AF is associated with a higher incidence of postoperative complications, especially thromboembolic manifestations and low cardiac output syndrome, particularly in patients with borderline left ventricular function.7 RF ablation involves complete isolation of the pulmonary veins and exclusion of the left atrial appendage, to prevent the pathway of transmission between both the left atrial appendage and the mitral valve to the pulmonary veins.8 The advantage of left atrial vs. biatrial ablation is debatable. Some studies found no significant difference between left-side and right-side ablation, except for an increase in cardiopulmonary bypass time,9 whereas other studies confirmed the efficacy of biatrial compared to left atrial ablation.10 Although the incidence of injury to important structures such as the circumflex artery is relatively high in monopolar compared to bipolar RF ablation, most studies found no difference between modes regarding the success rate.11 Some studies have used postoperative continuous monitoring, either invasive or noninvasive, to follow up patients.12,13 Continuous monitoring allows a higher degree of confidence in detecting the real incidence of sinus rhythm recovery and occurrence of transient attacks of arrhythmias, compared to the interval monitoring used in our study. Unfortunately, such modalities of monitoring were not available in our center during our study. Our in-hospital success rate for AF ablation was 84.12% with a 1-year success rate of 88.14%, which agrees with previous studies that documented success rates of 80% to 92% for concomitant AF ablation during mitral valve surgery.14,15 Most studies have shown the importance of postoperative antiarrhythmic drugs in maintaining and even restoring AF patients to sinus rhythm. Also, many studies have confirmed the
Table 3. Postoperative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Ventilation time (h) Intensive care unit stay (h) Hospital stay (days) Reexploration
6.48 4.65 58.52 11.91 8.18 1. 92 1 (1.9%)
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
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Asian Cardiovascular & Thoracic Annals 22(7)
importance of at least 3 months of postoperative antiarrhythmic medication to achieve the maximum success rate for the ablation procedure.16 In our study, 2 patients with postoperative persistent AF had restoration of sinus rhythm after 3 months. Many factors affect the success rate of RF ablation, but enlarged left atrium was reported in many studies to be the main cause for failure of ablation. Sunderland and colleagues17 considered left atrial size >6 cm to be a predictor of failure of AF ablation. Patients with rheumatic disease are more prone to failure because their atrial tissues are thicker and more fibrosed which impairs the penetration of RF power, and hence affects the isolation of the pulmonary veins.18 In our study, all patients with persistent AF post-ablation had rheumatic disease, with mean left atrial size >6 cm compared to 5.43 cm in patients with sinus rhythm. The limitations of this study include the relatively small number of patients, which did not allow us to perform multivariate analysis between patients with persistent AF and those with sinus rhythm, to analysis the factors for success or failure of RF ablation. However, we concluded that left atrial monopolar RF ablation during mitral valve surgery is a safe procedure with a high success rate, especially in nonrheumatic patients with left atrial size
Radiofrequency ablation of atrial fibrillation during mitral valve surgery
Asian Cardiovascular & Thoracic Annals 2014, Vol. 22(7) 807–810 ß The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492313519990 aan.sagepub.com
Farouk Oueida1, Mohamed Ahmed Elawady2 and Khalid Eskander1
Abstract Objectives: Atrial fibrillation is the most common form of arrhythmia in mitral valve disease. Radiofrequency ablation is most commonly used for atrial fibrillation ablation during mitral valve surgery. Methods: This prospective study evaluated the midterm outcomes of intraoperative radiofrequency atrial fibrillation ablation during mitral valve surgery. Results: 52 patients were eligible for the study. Fifteen (28.8%) had a transseptal approach and 37 had a left atriotomy. Mitral valve replacement was performed in 16 patients, mitral valve repair in 31, and tricuspid repair in 8. Mean crossclamp time was 58.14. 20.08 min, and mean cardiopulmonary bypass time was 71.28 20.31 min. The mean ablation time was 6.41 0.21 min. There was no postoperative mortality. Sinus rhythm was documented in 44 (84.6%) patients on discharge, and 8 (15.4%) were discharged with atrial fibrillation; 2 of them returned to sinus rhythm after 3 months. After 12 months of follow-up, 46 (88.5%) patients were in sinus rhythm. Conclusion: Left atrial monopolar radiofrequency ablation during mitral valve surgery is a safe procedure with a high success rate.
Keywords Anti-arrhythmia agents, atrial fibrillation, catheter ablation, heart atria, heart valve prosthesis implantation, mitral valve
Introduction Atrial fibrillation (AF) is the most common form of arrhythmia in mitral valve disease, with incidence ranging from 30% to 84%.1 AF may cause heart failure and thromboembolic complications, leading to increased morbidity and mortality, with a high financial burden. Medical treatment in persistent AF is not the best option due to high failure rates of up to 84%.2 The Cox maze operation with its modifications is the gold standard for surgical treatment of AF, with nearly 100% success rates, but it is a complex procedure needing surgical experience. The Cox maze also requires a long crossclamp time and there is a higher incidence of bleeding.3,4 This has led to the evolution of less invasive surgical techniques with the same surgical concepts as the Cox maze procedure but replacing the scissors in the cut-and-sew method by power sources to create the lines of conduction block without cutting the tissue. These include radiofrequency (RF), microwave, laser, high-frequency focused ultrasound, and cryoablation.5
Since the year 2000, RF has been one of the most commonly used methods for ablation.5,6 The aim of this study was to evaluate the midterm results of left atrial monopolar RF ablation for persistent AF during mitral valve surgery.
Patients and methods A prospective study was undertaken to evaluate the midterm results of intraoperative radiofrequency ablation during mitral valve operations in Saud Al Babtain 1 Cardiac Surgery Department, Saud Al-Babtain Cardiac Centre, Dammam, Saudi Arabia 2 Cardiothoracic Surgery Department, Banha Faculty of Medicine, Banha University, Egypt
Corresponding author: Mohamed Ahmed Elawady, MD, Cardiothoracic Surgery Department, Banha Faculty of Medicine, Banha University, Banha 2344, Egypt. Email: [email protected]
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
808
Asian Cardiovascular & Thoracic Annals 22(7)
Cardiac Center, Dammam, Saudi Arabia. After approval by the institutional ethics and research committee, all patients provided signed consent for surgery including the ablation procedure. Inclusion criteria were elective mitral valve surgery, left ventricular ejection fraction 535%, and persistent preoperative AF. Exclusion criteria were: age >70 years; chronic obstructive pulmonary disease; poor left ventricular function (ejection fraction 40-years old or with history of ischemic heart disease. All patients were anesthetized with propofol and fentanyl, using a target-controlled intravenous anesthesia protocol. Each patient had a central venous catheter and Swan-Ganz catheter with invasive monitoring of blood pressure. All patients had transesophageal echocardiography pre-bypass and immediately after weaning from cardiopulmonary bypass. Patients had either a median sternotomy or a limited right anterior
thoracotomy. All operations were performed using a conventional cardiopulmonary bypass machine with crossclamping of the aorta and cardioplegia. Cardiopulmonary bypass was conducted using a membrane oxygenator and moderate hypothermia. The mitral valve was approached by either a left or right atriotomy using a transseptal approach. RF ablation was performed under crossclamping after mitral valve repair or replacement. RF ablation was undertaken using a Medtronic Cardioblate 68000 Surgical Ablation System Generator Device and a model 60813 Standard Cardioblate Surgical Ablation Pen. The generator power was set at 30 W, and lesions were produced at a temperature of 70 C–80 C. Linear lesions in the left atrium were produced according to the scheme presented in Figure 1. Each 1-cm long segment of the ablation line was created by dragging the distal tip of the Cardioblate pen gently across the endocardial tissue under the surgeon’s vision, moving in an oscillating motion at 1 cms 1 for approximately 20 s until the targeted endocardium became pale. The first ablation line was created around the right and left pulmonary veins. One lesion connected the left lower pulmonary vein with the mitral annulus at the base of the posterior leaflet. The left atrial appendage was sewn in all patients. Two pacemaker wires were placed: one in the right atrium and the second in the ventricle; they were cut before patients were discharged home. Oral anticoagulation was administered to all patients. They were started on subcutaneous lowmolecular-weight heparin until the target international normalized ratio was reached. Oral anticoagulants were discontinued after the 3rd month in mitral valve repair cases with sinus rhythm. According to our protocol, all patients had an intraoperative amiodarone infusion with a loading dose of 300 mg followed by continuous infusion of a total of 1200 mg over the next 24 h. Amiodarone was administered orally for 3 months
Table 1. Preoperative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Mean age (years) Male Female Ejection fraction Mean PA pressure (mm Hg) Mean left atrial size (cm)
43.22 6.23 31 (59.6%) 21 (40.4%) 51.46% 6.59% 47.5 11.4 5.77 0.68
PA: pulmonary artery.
Figure 1. Scheme of ablation. Note: the left atrial appendage is sewn.
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
Oueida et al.
809
after discharge. All patients underwent transthoracic echocardiography before discharge, and a 12-lead ECG and transthoracic echocardiography at 1, 3, 6, and 12 months during outpatient visits. All demographic data, preoperative, operative, and postoperative data were collected, and statistical analysis was conducted using SPSS version 18.0 software (SPSS, Inc., Chicago, IL, USA). Values of continuous variables are expressed as mean standard deviation. Categorical variables are expressed as numbers and percentages.
Results Eight (15.4%) patients had a small right anterior thoracotomy approach, and 44 (84.6%) had a midline sternotomy. In 15 (28.8%) patients, the transseptal approach was used, the other 37 had a left atriotomy. Two (3.8%) patients had a left atrial thrombus. The left atrial appendage was closed in all patients. Mitral valve replacement was performed in 21 (40.4%) patients, and 31 (59.6%) had mitral valve repair. Table 2 summarizes the surgical data. Intraoperatively, 41 patients had sinus rhythm immediately, and 3 returned to sinus rhythm after electrical cardioversion. Thus on arrival at the intensive care unit, 44 patients had sinus rhythm; 6 of them had one or more attack of AF during hospital stay but returned to sinus rhythm pharmacologically with no need for electrical cardioversion. No patient required permanent pacemaker implantation before discharge. Sinus rhythm was documented in 44 (84.6%) patients on discharge, and 8 (15.4%) were discharged with AF. One patient was reexplored for bleeding. The postoperative data are summarized in Table 3. Superficial sternal wound infection was found in one (1.9%) patient. There was no hospital mortality. Mean left atrial size before discharge was 5.43 cm in patients with sinus rhythm, and 6.13 cm in those with persistent AF. Of the 8 patients discharged in AF,
Table 2. Operative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Mitral valve repair Mitral valve replacement Mechanical valve Tissue valve Tricuspid valve repair Cardiopulmonary bypass time (min) Crossclamp time (min) Ablation time (min)
31 21 6 15 8 71.28 20.31 53.14 17.08 6.41 0.21
2 retuned to sinus rhythm after 3 months. At the 6- and 12-month follow-up, the total number in sinus rhythm was unchanged at 46, giving a total success rate of 88.46%.
Discussion Persistent postoperative AF is associated with a higher incidence of postoperative complications, especially thromboembolic manifestations and low cardiac output syndrome, particularly in patients with borderline left ventricular function.7 RF ablation involves complete isolation of the pulmonary veins and exclusion of the left atrial appendage, to prevent the pathway of transmission between both the left atrial appendage and the mitral valve to the pulmonary veins.8 The advantage of left atrial vs. biatrial ablation is debatable. Some studies found no significant difference between left-side and right-side ablation, except for an increase in cardiopulmonary bypass time,9 whereas other studies confirmed the efficacy of biatrial compared to left atrial ablation.10 Although the incidence of injury to important structures such as the circumflex artery is relatively high in monopolar compared to bipolar RF ablation, most studies found no difference between modes regarding the success rate.11 Some studies have used postoperative continuous monitoring, either invasive or noninvasive, to follow up patients.12,13 Continuous monitoring allows a higher degree of confidence in detecting the real incidence of sinus rhythm recovery and occurrence of transient attacks of arrhythmias, compared to the interval monitoring used in our study. Unfortunately, such modalities of monitoring were not available in our center during our study. Our in-hospital success rate for AF ablation was 84.12% with a 1-year success rate of 88.14%, which agrees with previous studies that documented success rates of 80% to 92% for concomitant AF ablation during mitral valve surgery.14,15 Most studies have shown the importance of postoperative antiarrhythmic drugs in maintaining and even restoring AF patients to sinus rhythm. Also, many studies have confirmed the
Table 3. Postoperative data of 52 patients with atrial fibrillation and mitral valve disease. Variable
No. of patients
Ventilation time (h) Intensive care unit stay (h) Hospital stay (days) Reexploration
6.48 4.65 58.52 11.91 8.18 1. 92 1 (1.9%)
Downloaded from aan.sagepub.com at Stockholm University Library on July 27, 2015
810
Asian Cardiovascular & Thoracic Annals 22(7)
importance of at least 3 months of postoperative antiarrhythmic medication to achieve the maximum success rate for the ablation procedure.16 In our study, 2 patients with postoperative persistent AF had restoration of sinus rhythm after 3 months. Many factors affect the success rate of RF ablation, but enlarged left atrium was reported in many studies to be the main cause for failure of ablation. Sunderland and colleagues17 considered left atrial size >6 cm to be a predictor of failure of AF ablation. Patients with rheumatic disease are more prone to failure because their atrial tissues are thicker and more fibrosed which impairs the penetration of RF power, and hence affects the isolation of the pulmonary veins.18 In our study, all patients with persistent AF post-ablation had rheumatic disease, with mean left atrial size >6 cm compared to 5.43 cm in patients with sinus rhythm. The limitations of this study include the relatively small number of patients, which did not allow us to perform multivariate analysis between patients with persistent AF and those with sinus rhythm, to analysis the factors for success or failure of RF ablation. However, we concluded that left atrial monopolar RF ablation during mitral valve surgery is a safe procedure with a high success rate, especially in nonrheumatic patients with left atrial size
