Endocardial radiofrequency ablation during mitral valve surgery: effect on cardiac rhythm, atrial size, and function

Abstract

Background: Restoration of sinus rhythm is thought to lead to a reduction in left atrial size and to recovery of atrial contraction. We aimed to investigate changes in atrial size and function in patients undergoing radiofrequency ablation for atrial fibrillation during mitral valve surgery.

Methods: In a prospective study, 70 patients (64 +/- 10 years) with mitral valve disease and atrial fibrillation underwent mitral surgery and left atrial endocardial radiofrequency ablation. Evaluation was achieved before surgery, at 7 days, 5 months, and 22 months after surgery. Maximal right and left atrial areas, left atrial diameter, and volume were measured. Atrial filling fraction (ventricular filling related to atrial contraction to total ventricular filling ratio) was used as an index of atrial contraction.

Results: At the end of follow-up (22 +/- 10 months) most patients (91%) were in sinus rhythm. Actuarial freedom from atrial fibrillation recurrence was 62.5% after 2 years. Atrial size decreased, with a significant improvement in right (36 +/- 15 vs 10 +/- 20% preoperatively, p < 0.0001) and left (25 +/- 12 vs 7 +/- 14%, p < 0.0001) atrial filling fraction. Despite similar preoperative atrial size, at the end of follow-up atrial fibrillation recurrence was associated with a higher left atrial volume than in patients free of recurrence (41 +/- 14 vs 32 +/- 9 mL/m2, p = 0.004). Independent predictors of atrial fibrillation recurrence were previous mitral procedure (p = 0.029), left ventricular ejection fraction (p = 0.033), and mitral rheumatic lesion (p = 0.034).

Conclusions: Left atrial radiofrequency ablation for atrial fibrillation during mitral surgery is an effective procedure restoring sinus rhythm. Right and left atrial size was significantly reduced, with a recovery in atrial contraction.