Epicardial Connections Involving Pulmonary Veins: The Prevalence, Predic-tors and Implications for Ablation Outcome.

Background - The presence of epicardial connections (ECs) between pulmonary veins (PVs) and other anatomical structures may hinder PV isolation. In this study we analyzed their prevalence, location, associated factors and clinical implications. Methods - Five hundred and thirty-four consecutive patients with atrial fibrillation (AF) undergoing radiofrequency ablation were included. We considered that an EC was present if: 1) the first pass around the PV antrum did not produce PV isolation and 2) subsequent atrial activation during PV pacing showed that the earliest site was located away from the ablation line and later activation sites were observed near the ablation line. Clinical, and electrophysological variables were collected from all patients. Patients were followed during 12.9±9.4 months and any documented atrial tachyarrhythmia after the 3-month blanking period was classified as a recurrence. Results - Out of the 534 patients included, 72 (13.5%) were found to have 81 ECs. There was a significant association between the presence ECs and structural heart disease (SHD) (15.3% in patients without ECs vs. 36.5% in patient with ECs; p<0.001) and patent foramen ovale (PFO) (4.6% vs. 13.5%; p=0.002). The presence of a left common trunk was significantly associated with the absence of ECs (29.6% in patients without ECs vs 16.2% in patients with ECs; p=0.014). Patients with ECs had lower acute success in PV isolation compared with patients without ECs (99.1% vs. 86.1%; p<0.001). After adjusting for age, sex, type of AF, LA area, hypertension, SHD, presence of left common trunk, patent foramen ovale and time for AF diagnosis to the ablation we found a significantly higher risk of atrial tachyarrhythmia recurrences in patients with ECs compared with patients without ECs (hazard ratio: 1.7; 95% confidence inter-val: 1.1-2.9; p=0.04). Conclusions - ECs between PVs and other adjacent structures are frequent in patient with AF (prevalence: 13.5%). SHD and a PFO are strongly associated with the presence of ECs. ECs reduce the acute and chronic success of PV isolation.