Biventricular pacing improves cardiac function and prevents further left atrial remodeling in patients with symptomatic atrial fibrillation after atrioventricular node ablation

Background Randomized trials have demonstrated benefits of biventricular (BiV) pacing in patients with advanced heart failure, intraventricular conduction delay, and atrial fibrillation (AF) postatrioventricular (AV) node ablation. The AV Node Ablation with CLS and CRT Pacing Therapies for Treatment of AF trial (AVAIL CLS/CRT) was designed to demonstrate superiority of BiV pacing in patients with AF after AV node ablation, to evaluate its effects on cardiac structure and function, and to investigate additional benefits of Closed Loop Stimulation (R) (CLS) (BIOTRONIK, Berlin, Germany). Methods Patients with refractory AF underwent AV node ablation and were randomized (2:2:1) to BiV pacing with CLS, BiV pacing with accelerometer, or right ventricular (RV) pacing. Echocardiography was performed at baseline and 6 months, with paired data available for 108 patients. Results The RV pacing contributed to significant increase in left atrial volume, left ventricular (LV) end-systolic volume, and LV mass compared to BiV pacing. Ejection fraction decreased insignificantly with RV pacing compared to significant increase with BiV pacing. Interventricular dyssynchrony significantly decreased with BiV compared with RV pacing. Closed Loop Stimulation (R) did not result in additional echocardiographic changes; heart rate distribution was significantly wider with CLS. All groups showed significant improvement in 6-minute walk distance, quality-of-life score, and New York Heart Association class. Conclusion In conclusion, RV pacing results in significant increase in left atrial volume, LV mass, and worsening of LV contractility compared to patients receiving BiV pacing post-AV node ablation for refractory AF. Closed Loop Stimulation (R) was not associated with additional structural changes but resulted in significantly wider heart rate distribution. (Am Heart J 2010;159:264-70.)