Minimal energy requirement for external cardioversion and catheter ablation for long-standing persistent atrial fibrillation

Abstract

BACKGROUND: The minimal energy requirement (Emin) for electrical cardioversion (ECV) reflects the atrial substrate in patients with long-standing persistent atrial fibrillation (L-PeAF), but the relationship between EminECV and radiofrequency catheter ablation (RFCA) has not yet been studied. We hypothesize that EminECV before ablation (EminECVpre) predicts clinical outcome of RFCA, and that catheter ablation reduces EminECVpost.

METHODS: We included 172 patients with L-PeAF who underwent RFCA (79.7% males, 57.5±10.0 years) due to AF recurrence after ECV with an anti-arrhythmic drug (AAD). ECV began with 70J (patch electrode on anterior-posterior position) and was serially increased to 100, 150, 200, and 250J until sinus rhythm was achieved, at an average 5.0±5.6 months before RFCA. After RFCA, ECV was repeated (ECVpost) in 42 patients with recurrent AF that was not controlled by AAD.

RESULTS: (1) During 34.8±20.0 months of follow-up after RFCA, 103 patients (59.9%) showed clinical recurrence of AF after RFCA. EminECVpre was significantly higher in patients with recurrent AF (129.0±58.6J) than those who remained in sinus rhythm (94.2±39.4J, p<0.001). (2) EminECVpre ≥150J (HR=3.31, 95% CI 2.18-5.03, p<0.001) and left atrial volume index (HR=1.02, 95% CI 1.00-1.04, p=0.021) were significantly associated with post-RFCA recurrence. (3) Shorter post-RFCA recurrence timing was also independently related to EminECVpre (β=-0.147, 95% CI -0.20 to -0.09, p<0.001). (4) Among 103 patients with recurrent AF after RFCA, 42 AAD-resistant AF patients underwent ECVpost. EminECVpost (100.9±50.8J) was significantly lower than EminECVpre (130.0±66.1J, p=0.006).

CONCLUSIONS: Higher EminECVpre was independently associated with clinical recurrence and earlier recurrence timing of AF after catheter ablation among patients with AAD-resistant L-PeAF. Catheter ablation for L-PeAF significantly reduces EminECV.