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Left-Atrial Ablation of AFib During Mitral Valve Surgery

Promising findings from a randomized trial in patients with continuous atrial fibrillation

Nearly half of patients who are referred for mitral valve surgery have continuous atrial fibrillation (AF). Adding a left-atrial radiofrequency (RF) ablation procedure for AF during open-heart surgery has been shown to improve the chances of restoring postsurgery sinus rhythm, but supporting studies have been nonrandomized or underpowered. Now, in a randomized trial, 97 referral patients (mean age, 67) with continuous AF of at least 6 months’ duration underwent mitral valve surgery, either alone (control) or in conjunction with unipolar-RF ablation of the left atrium (a partial "maze" procedure like that developed by Cox). Mitral valve repair was done in 74% of patients and mitral valve replacement in 26%.

At 1-year follow-up, ECG evidence of sinus rhythm was significantly more common in the RF-ablation group than in the control group (44.4% vs. 4.5%). Restoration of sinus rhythm was associated with greater improvement in exercise tolerance and greater reduction in B-type natriuretic peptide levels. The RF-ablation and control groups did not differ significantly in rates of complications or perioperative mortality (3 and 4 deaths, respectively).

Comment: This is the first randomized trial of substantial size to show that a concomitant left-atrial RF-ablation procedure can reduce the incidence of postoperative atrial fibrillation after mitral valve surgery in patients with continuous AF. Furthermore, the benefit came without an increase in complications. Still sobering is that fewer than half of patients were in sinus rhythm at 1-year follow-up. If 7-day Holter monitoring had been done, many of the patients not in sinus rhythm likely would have shown evidence of asymptomatic paroxysmal AF. Does the disappointing sinus-rhythm data reflect lack of completion of the original maze lesion set, or perhaps that RF energy created nontransmural lesions? It’s clear that more work remains. For now, given these results, one ought to consider left-atrial RF ablation in all AF patients who undergo mitral valve surgery.

— Hugh Calkins, MD

Published in Journal Watch Cardiology December 2, 2005

Citation(s):

Doukas G et al. Left atrial radiofrequency ablation during mitral valve surgery for continuous atrial fibrillation: A randomized controlled trial. JAMA 2005 Nov 9; 294:2323-9.

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• Medline abstract (Free)

Sundt TM and Gersh BJ. Making sense of the maze: Which patients with atrial fibrillation will benefit? JAMA 2005 Nov 9; 294:2357-9.

• Original article (Subscription may be required)
• Medline abstract (Free)