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Asian Cardiovascular and Thoracic Annals http://aan.sagepub.com/ Radiofrequency ablation of atrial fibrillation during mitral valve surgery Farouk Oueida, Mohamed Ahmed Elawady and Khalid Eskander Asian Cardiovascular and Thoracic Annals published online 21 January 2014 DOI: 10.1177/0218492313519990 The online version of this article can be found at: http://aan.sagepub.com/content/early/2014/01/20/0218492313519990 Published by: http://www.sagepublications.com On behalf of: The Asian Society for Cardiovascular Surgery Additional services and information for Asian Cardiovascular and Thoracic Annals can be found at: Email Alerts: http://aan.sagepub.com/cgi/alerts Subscriptions: http://aan.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav >> OnlineFirst Version of Record - Jan 21, 2014 What is This? Downloaded from aan.sagepub.com by guest on June 5, 2014 Original Article Radiofrequency ablation of atrial fibrillation during mitral valve surgery Asian Cardiovascular & Thoracic Annals 0(0) 1-4 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 cross- clamp time was 58.14. Æ 20.08 min, and mean cardiopulmonary bypass time was 71.28 Æ 20.31 min. The mean ablation time was 6.41 Æ 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 ran- ging 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 need- ing 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 cutand-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 abla- tion 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 by guest on June 5, 2014 2 Asian Cardiovascular & Thoracic Annals 0(0) Cardiac Center, Dammam, Saudi Arabia. After approval by the institutional ethics and research com- mittee, all patients provided signed consent for surgery including the ablation procedure. Inclusion criteria were elective mitral valve surgery, left ventricular ejec- tion fraction 535%, and persistent preoperative AF. Exclusion criteria were: age >70 years; chronic obstructive pulmonary disease; poor left ventricular function (ejection fraction <35%); renal failure on regular dialysis; active endocarditis; emergency, urgent, or redo surgery; postoperative low cardiac output syndrome; and associated ischemic heart dis- ease. There were 52 patients eligible for the study: 18 (34.6%) had rheumatic mitral disease, 34 (65.4%) had degenerative mitral valve disease; and 8 (15.4%) also had tricuspid valve disease. Table 1 summarizes their preoperative data. From the day of admission until the day of dis- charge, all patients had a daily standard 12-lead elec- trocardiogram (ECG). Postoperatively, all patients in the surgical intensive care unit were monitored via a bedside arrhythmia monitor (Siemens SC 9000XL). Postoperatively, they were monitored in the ward by continuous ECG telemetry monitoring (Siemens). If a patient developed AF, a 12-lead ECG was obtained; a second 12-lead ECG was carried out if the patient returned to sinus rhythm. All patients had preoperative transthoracic echocardiography using a Vivid 7 machine (GE Medical Systems, Vingmed, Norway). Patients with suspected left atrial thrombus had pre- operative transesophageal echocardiography. Coronary angiography was carried out in patients >40years 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 wean- ing 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 mem- brane 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 701C-801C. Linear lesions in the left atrium were produced according to the scheme presented in Figure 1. Each 1-cm long seg- ment of the ablation line was created by dragging the distal tip of the Cardioblate pen gently across the endo- cardial tissue under the surgeon's vision, moving in an oscillating motion at 1 cmÁsÀ1 for approximately 20 s until the targeted endocardium became pale. The first ablation line was created around the right and left pul- monary veins. One lesion connected the left lower pul- monary 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) 43.22 Æ 6.23 Male 31 (59.6%) 21 Female (40.4%) Ejection fraction 51.46% Æ 6.59% Mean PA pressure (mm Hg) 47.5 Æ 11.4 5.77 Æ Mean left atrial size (cm) 0.68 PA: pulmonary artery. Figure 1. Scheme of ablation. Note: the left atrial appendage is sewn. Downloaded from aan.sagepub.com by guest on June 5, 2014 Oueida et al. 3 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 ana- lysis was conducted using SPSS version 18.0 software (SPSS, Inc., Chicago, IL, USA). Values of continuous variables are expressed as mean Æ 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 dis- charged with AF. One patient was reexplored for bleed- ing. 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 31 Mitral valve replacement 21 2 retuned to sinus rhythm after 3 months. At the 6- and 12month 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 border- line left ventricular function. 7 RF ablation involves complete isolation of the pulmonary veins and exclu- sion of the left atrial appendage, to prevent the path- way 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 difer- ence between left-side and right-side ablation, except for an increase in cardiopulmonary bypass time,9 whereas other studies confirmed the efcacy of biatrial compared to left atrial ablation. 10 Although the inci- dence of injury to important structures such as the cir- cumflex artery is relatively high in monopolar compared to bipolar RF ablation, most studies found no diference 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 inci- dence of sinus rhythm recovery and occurrence of tran- sient 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. Mechanical valve 6 Tissue valve 15 Variable No. of patients Tricuspid valve repair 8 Ventilation time (h) 6.48 Æ 4.65 Cardiopulmonary bypass time (min) 71.28 Æ 20.31 Intensive care unit stay (h) 58.52 Æ 11.91 Crossclamp time (min) 53.14 Æ 17.08 Hospital stay (days) 8.18 Æ 1. 92 Ablation time (min) 6.41 Æ 0.21 Reexploration 1 (1.9%) Downloaded from aan.sagepub.com by guest on June 5, 2014 4 Asian Cardiovascular & Thoracic Annals 0(0) 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 restor- ation of sinus rhythm after 3 months. Many factors afect 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 col- leagues17 considered left atrial size >6 cm to be a pre- dictor 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 afects the isolation of the pulmonary veins.18 In our study, all patients with persistent AF post-abla- tion 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 <6 cm. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. 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J Interv Card Electrophysiol 2011; 32: 29-35. 14. Mesana TG, Kulik A, Ruel M, et al. Combined atrial fibrillation ablation with mitral valve surgery. J Heart Valve Dis 2006; 15: 515-520. 15. Cheng DC, Ad N, Martin J, et al. Surgical ablation for atrial fibrillation in cardiac surgery: a meta-analysis and systematic review. Innovations 2010; 5: 84-96. 16. 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: 860867. 17. Sunderland N, Maruthappu M and Nagendran M. What size of left atrium significantly impairs the success of maze surgery for atrial fibrillation? Interact Cardiovasc Thorac Surg 2011; 13: 332-338. 18. Chaiyaroj S, Ngarmukos T and Lertsithichai P. Predictors of sinus rhythm after radiofrequency maze and mitral valve surgery. Asian Cardiovasc Thorac Ann 2008; 16: 292-297. Downloaded from aan.sagepub.com by guest on June 5, 2014