ORIGINAL CONTRIBUTION Left Atrial Radiofrequency Ablation During Mitral Valve Surgery for Continuous Atrial Fibrillation A Randomized Controlled Trial George Doukas, FRCSI Context Although left atrial radiofrequency ablation (RFA) is increasingly used for Nilesh J. Samani, MD, FRCP the treatment of chronic atrial fibrillation during mitral valve surgery, its efficacy to Christos Alexiou, FRCS, PhD restore sinus rhythm and any resulting benefits have not been examined in the con- text of an adequately powered randomized trial. Mehmet Oc, MD Objective To determine whether intraoperative RFA of the left atrium increases the Derek T. Chin, MD long-term restoration of sinus rhythm and improves exercise capacity. Peter G. Stafford, MD Design, Setting, and Patients Randomized, double-blind trial performed in a single Leong L. Ng, MD UK tertiary referral center with enrollment between December 2001 and November 2003. A total of 101 patients referred for mitral valve surgery with at least 6 months’ Tomasz J. Spyt, FRCS, MD history of uninterrupted atrial fibrillation were assessed for eligibility; 97 were en- TRIAL FIBRILLATION IS A FRE- rolled. Patients were followed up for 12 months. quent and important con- Intervention Patients were randomly assigned to undergo mitral valve surgery and tributor to symptoms and RFA of the left atrium (n=49) or mitral valve surgery alone (controls; n=48). morbidity in patients with Main Outcome Measures The primary outcome measure was presence of sinus Amitral valve disease. More than 40% of rhythm at 12 months; secondary measures were patient functional status and exercise patients referred for mitral valve sur- capacity (assessed by shuttle-walk test), left atrial contractility, and left atrial and left gery have continuous atrial fibrilla- ventricular dimension and function and plasma levels of B-type natriuretic peptide. tion.1-3 Patients who remain in atrial fi- Results At 12 months, sinus rhythm was present in 20 (44.4%) of 45 RFA patients brillation following mitral valve surgery and in 2 (4.5%) of 44 controls (rate ratio, 9.8; 95% CI, 2.4-86.3; PϽ.001). Restora- may have lower survival 3 to 5 years tion of sinus rhythm in the RFA group was accompanied by a greater improvement in ϩ ϩ later4 compared with those in sinus mean (SD) shuttle-walk distance compared with controls ( 94 [102] m vs 48 [82] rhythm, although this has not been ob- m; P=.003) and a greater reduction in the plasma level of B-type natriuretic peptide 5 (−104 [87] fmol/mL vs −51 [82] fmol/mL; P=.03). Patients randomized to receive RFA served in all studies. had similar rates of postoperative complications and deaths as control patients. For a long time, it was believed that atrial fibrillation occurs as a result of a Conclusions Radiofrequency ablation of the left atrium during mitral valve surgery multiple-circuit reentry mechanism. for continuous atrial fibrillation significantly increases the rate of sinus rhythm resto- ration 1 year postoperatively, improving patient exercise capacity. On the basis of its This notion is now challenged by evi- efficacy and safety, routine use of RFA of the left atrium during mitral valve surgery dence suggesting that, in some cir- may be justified. cumstances, even continuous atrial Trial Registration ClinicalTrials.gov Identifier: NCT00238706. fibrillation may be organized by 1 or a JAMA. 2005;294:2323-2329 www.jama.com small number of high-frequency sources (rotors) in the left atrium, a novel surgical mode for treatment of Author Affiliations: Departments of Cardiac Surgery (Drs especially in the vicinity of the pulmo- Doukas, Alexiou, Oc, and Spyt) and Cardiology (Drs nary veins.6 Hence, radiofrequency atrial fibrillation. It is based on the Samani, Chin, and Stafford), Glenfield Hospital, Uni- original concept of the maze proce- versity Hospitals of Leicester NHS Trust, and the Depart- ablation (RFA) of the left atrium dur- 7 ment of Cardiovascular Sciences, University of Leicester ing open-heart surgery has emerged as dure and aims to eliminate anatomi- (Drs Doukas, Samani, Ng, and Spyt), Leicester, England. cally determined reentrant circuits by Correspondence: George Doukas, FRCSI, Department creating contiguous lines of scar tissue of Cardiac Surgery, Glenfield Hospital, Groby Road, Leic- For editorial comment see p 2357. ester LE3 9QP, England (doukas_george@hotmail between the pulmonary veins and the .com). ©2005 American Medical Association. All rights reserved. (Reprinted) JAMA, November 9, 2005—Vol 294, No. 18 2323 Downloaded From: https://jamanetwork.com/ on 09/25/2021 LEFT ATRIAL RADIOFREQUENCY ABLATION IN MITRAL VALVE SURGERY mitral valve annulus.7,8 Although RFA and the superioinferior left atrial atrium size was studied in the 2-dimen- therapy of the left atrium is being diameter (Ն60 vs Ͻ60 mm). These 3 sional mode on apical views. Mitral in- increasingly offered to patients with variables produced 8 subgroups. Ran- flow velocity was obtained by pulse- chronic atrial fibrillation who are domized blocks of between 4 and 6 wave Doppler examination from the undergoing mitral valve surgery,9-11 its were prepared for each subgroup in apical 4-chamber view. efficacy has not been tested in the con- advance by computer-generated num- text of an adequately powered ran- bers, and individual allocations were Surgery and RFA Procedure domized study. The aims of this pro- placed in sealed envelopes. Assign- Operations were performed between spective randomized clinical trial were ment took place on the day of the December 2001 and November 2003 to evaluate early and late outcomes operation by picking the next enve- by a single surgeon (T.J.S.). Access to following left atrial RFA during mitral lope for the relevant group by a person the mitral valve was obtained through valve surgery for treatment of continu- masked to previous allocations. In the left atrium. If tricuspid valve sur- ous atrial fibrillation and to assess the addition, the participants and the gery was undertaken, a transeptal functional effects of restoration of assessors of outcomes were blinded to approach was used. A Cosgrove- sinus rhythm. group assignment. Edwards annuloplasty band was rou- tinely inserted during mitral valve re- METHODS Outcome End Points pair, tricuspid valve repair, or both. Participants and Sample Size The left atrial appendage was over- The trial was conducted within the De- The primary outcome end point was the sewn from within in all patients in both partments of Cardiac Surgery and Car- presence of sinus rhythm at 12 months. groups. diology, Glenfield Hospital, Leicester, Secondary end points included pa- Radiofrequency lesions were cre- England. Patients requiring mitral valve tient functional status and exercise ca- ated endocardially with a handheld surgery and who also had a history of pacity, left atrial contractility, and left monopolar, 7-electrode, temperature- continuous atrial fibrillation were eli- atrial and left ventricular dimension and controlled probe (EP Technologies, gible. The term continuous atrial fibril- function and plasma levels of B-type na- Boston Scientific Corp, San Jose, lation denotes the presence of uninter- triuretic peptide (BNP). Calif). Radiofrequency generators rupted atrial fibrillation for at least 6 At the time of study design, avail- were set at 100 W and 70°C. Radiofre- months that showed no evidence of able data on the long-term efficacy of quency waves were delivered for 120 spontaneous reversibility to sinus RFA during mitral valve surgery sug- seconds to achieve transmural lesions, rhythm and was not possible to revert gested a reduction in postoperative as previously described.10 The left with medications or direct current car- atrial fibrillation of 64%.9 Assuming atrial incision was complemented dioversion. Patients with sick sinus syn- that after mitral valve surgery alone, by a semilunar RFA line to isolate the drome, uncontrolled hyperthyroid- 85% of those who were in atrial fibril- right pulmonary veins. The left pul- ism, permanent pacemaker, or previous lation preoperatively would continue monary veins were then encircled and cardiac surgery were excluded. The pro- to be in atrial fibrillation,12 approxi- a line was drawn connecting the 2 tocol was approved by the Leicester- mately 100 patients (50 in each encircling lines, the obliterated left shire Research Ethics Committee (ref- group) were required to detect a 30% atrial appendage, and the mitral valve erence No. 7503). Written informed reduction in atrial fibrillation with a annulus. consent was obtained from all partici- power of 90% at the .05 level of statis- pants, and the recommendations of the tical significance. This would allow for Postoperative Management revised version of the Declaration of up to 12% of patients being lost to and Follow-up Helsinki were met. follow-up or dying within the study Cardiac rhythm was continuously period. monitored for 48 hours. Thereafter, Interventions and daily 12-lead electrocardiograms Randomization Process Preoperative Assessment (ECGs) were performed for the dura- Patients were randomly assigned to Demographics and clinical data were tion of hospitalization. Per protocol, all undergo mitral valve surgery alone or prospectively recorded. The shuttle- patients were given amiodarone (or so- mitral valve surgery plus RFA of the walk test (SWT), a validated instru- talol if amiodarone was not tolerated) left atrium. Additional cardiac proce- ment for assessing functional capac- for at least 3 months. In patients who dures were performed as required. ity,13 was carried out in all patients. were in stable sinus rhythm, the anti- Blocked stratified randomization by Transthoracic echocardiography was arrhythmic agent was stopped at 3 patient characteristics was used. The performed to examine mitral valve func- months. Those who developed persis- variables used were age (Ն70 vs Ͻ70 tion, left atrium dimensions, atrial tent atrial fibrillation during the hos- years), etiology of the mitral valve dis- transport function, and left ventricu- pital stay underwent cardioversion ease (rheumatic vs nonrheumatic), lar dimension and function. The left within 24 hours.