Pulmonary veins branching pattern, assessed by magnetic resonance, does not affect transcatheter atrial fibrillation ablation outcome.

Aim: The aim of the present study is to provide, in a large cohort of patients, a description of the left atrium (LA) and pulmonary veins (PV) anatomy in relation to ablation outcome.

Background: The role of LA imaging, assessed before transcatheter ablation of atrial fibrillation (AF), is unknown.

Methods: 330 patients referred for transcatheter ablation of AF (paroxysmal 62.7%; persistent 25.5%; long-standing 11.8%) underwent contrast-enhanced magnetic resonance imaging (MRI) before the procedure. Transcatheter ablation was performed aiming to AF interruption and/or absence of inducibility. Patients were followed clinically, by ECG, and 24-hour Holter ECG at 1-3-6-12-18-24 months.

Results: The MRI preceding the procedure depicted a typical PV branching pattern, two left and two right, in 130 (39.4%) patients; 117 (35.4%) presented common left trunk (short and long) and 75 (22.7%) at least one accessory PV. Mean atrial volume was 142.0 +/- 48.5 ml. The ablation procedure resulted successful, after 15.6 +/- 7.2 months follow-up, in 174 (52.7%) patients. PV branching pattern did not relate (P = 0.304) to ablation outcome. A multiple Cox proportional hazard model, adjusted for potential confounders, proved that only LA volume was independently related to ablation outcome (HR 1.007, 95% CI 1.003-1.011; P = 0.001). A LA cut-off volume of 135 ml emerged as a significant predictor of ablation failure (ROC curve area 0.651, 95% CI 0.591-0.710; P < 0.001).

Conclusions: Less than half of the patients referred for transcatheter AF ablation present a typical PV branching pattern; the PV branching pattern, however, does not affect ablation outcome. LA volume strongly predicts AF ablation outcome.