Efficacy of Three Different Ablative Procedures to Treat Atrial Fibrillation in Patients with Valvular Heart Disease: A Randomised Trial

K.E.M. Hospital, Mumbai, India.
Heart, Lung and Circulation (Impact Factor: 1.44). 07/2008; 17(3):232-40. DOI: 10.1016/j.hlc.2007.10.003
Source: PubMed


Various modifications have been proposed to the original Cox's Maze procedure due to concerns about the long bypass and cross clamp times. The efficacy of these procedures has been studied and reported. We conducted a randomised prospective study to compare three procedures, differing in extent, of ablation in patients in atrial fibrillation who were undergoing surgery for rheumatic valvular heart disease. These procedures utilised radiofrequency in the bipolar mode. The extent of ablation was (1) biatrial (replication of the Cox Maze) (2) left atrial portion of the Cox Maze and (3) pulmonary vein isolation along with a control group (the No Maze group). Conversion rate to sinus rhythm was studied over a mid-term follow-up period.
A total of 160 patients were studied with 40 patients in each group. Antiarrhythmic drugs were not used in the three months preceding surgery and for seven days postoperatively. The patients underwent surgery for their valve disease along with the ablative procedure as per randomisation using radiofrequency microbipolar coagulation and cryoablation. They were followed up and were evaluated for symptomatic improvement, rhythm with ECG documentation and 2D echocardiography.
Follow-up was available for 133 patients. Mid-term results showed that sinus rhythm was restored in 62.5% patients of Biatrial Maze group and 57.5% in the Left Atrial Maze. In the Pulmonary Vein Isolation Maze group, 67.5% patients converted to NSR whereas in the No Maze group only 20% patients were in sinus rhythm (p value for all the groups was 0.001 when compared to the No Maze group). The incidence of other arrhythmias was not significant and there were no other major complications. All the patients in sinus rhythm at follow-up were in NYHA functional class I-II and showed good effort tolerance.
Results achieved with the three ablative procedures are comparable. Therefore lesser procedures viz. Left Atrial Maze and the Pulmonary Vein Isolation Maze procedures must be studied further with the additional use of antiarrhythmic drugs.

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Available from: Vasudev Baburaya Pai, Jul 13, 2014
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    • "There is no doubt that bipolar radiofrequency (RF) ablation is better than unipolar RF ablation to cure the atrial fibrillation (AF) because of the full transmurality achieved almost exclusively by the bipolar RF. I have discussed this matter previously [2] [3]. The presumed basis of successful AF ablation is production of myocardial lesions that block the propagation of AF wave fronts from a rapidly firing triggering source or modification of the arrhythmogenic substrate responsible for re-entry. "
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    ABSTRACT: A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether, in patients undergoing cardiac surgery, concomitant bipolar radiofrequency ablation had an acceptable success rate to justify the additional procedure. Altogether 263 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The consensus in the literature was that bipolar radiofrequency ablation was highly successful in restoring sinus rhythm. One meta-analysis of six non-randomized studies demonstrated that 76% of patients were in sinus rhythm compared with 16% in atrial fibrillation 3 months postoperatively. One randomized controlled trial found that the sinus rhythm conversion rate for any maze procedure was highly significant compared with the control group (P = 0.001). Another found that Cardioblate radiofrequency ablation was significantly better at restoring sinus rhythm at 1 year (75 vs 39% control, P = 0.019). Prospective studies showed a similar rate of sinus rhythm return at 1 year (89%). Notably some studies demonstrated a significant reduction in the New York Heart Association class when sinus rhythm was restored compared with those remaining in atrial fibrillation (P < 0.0001), demonstrating the value of this procedure beyond simply restoring sinus rhythm. In another study, the investigators found that both ablation and total procedure times were shorter with bipolar compared with monopolar ablation. These authors strongly recommend bipolar radiofrequency ablation due to a shorter procedure time, ability to avoid performing a standard left atriotomy and a greater guarantee of transmurality. With the current limited evidence, we conclude that bipolar radiofrequency ablation has a higher success rate in restoring sinus rhythm as an adjunct to cardiac surgery compared with no ablation for at least 1 year. The procedure had a high survival rate. There is randomized evidence to suggest the superiority of bipolar radiofrequency ablation over microwave ablation but limited evidence to suggest the superiority of bipolar over unipolar radiofrequency ablation. Factors found to be accurate predictors of ablation failure include a larger preoperative atrial diameter, permanent vs paroxysmal atrial fibrillation and longer duration of atrial fibrillation.
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