Introduction
Pulmonary vein (PV) isolation is the cornerstone of ablative treatment in patients with symptomatic paroxysmal and persistent atrial fibrillation (AF).1 It is performed with a wide antral approach is an effective strategy in the prevention of AF.2 Wider circumferential lesion areas are associated with longer procedure durations and, occasionally, carina ablation is required to achieve electrical isolation.3
Several factors explain the importance of the carina in preventing PV isolation. A postmortem study4 demonstrated the transmural myocardial thickness of the venoatrial junction as being the greatest at the carina region. Therefore, a thicker myocardial sleeve may disrupt creation of a transmural lesion. Another postmortem study5 described a case with muscular strands connecting the right PVs to the right atrium (RA) at the posterior interatrial groove, which could provide epicardial input from the RA to the right PV carina. Recent clinical studies demonstrated electrophysiological evidence confirming the presence of an epicardial connection (EC) between the PV and the left atrium (LA) or RA in patients with AF who underwent catheter ablation.6-8However, the assessment strategies for EC are not unified (e.g., whether assessment must be performed during sinus rhythm or PV pacing and before or after ablation). Owing to the multiple interatrial connections, including the Bachmann bundle, coronary sinus, and EC between the RA and right PVs,6 activation patterns of the LA are assumed to change depending on the origin of the right atrial impulses. Therefore, pacing from more than one site may be useful in distinguishing these pathways. Therefore, we hypothesized that an additional RA posterior wall (RAPW) pacing with RA appendage (RAA) pacing can detect ECs of the right pulmonary vein (RPV) carina more clearly in patients with AF undergoing catheter ablation.
Furthermore, factors associated with ECs have not been well clarified. Patients with AF have pathophysiological changes within the atria, such as fibrosis and fatty infiltration, resulting in conduction disturbance.9,10 A study using an obese sheep model identified conduction abnormalities related to the infiltration of the posterior left atrial muscle by epicardial fat.11Therefore, we presumed that the amount of epicardial adipose tissue (EAT) can affect the presence of the ECs.
The primary aim of this study was to prove the utility of RAPW pacing compared with RAA pacing in the detection of the ECs. Second, we evaluated the requirement for additional carina ablation after circumferential PV ablation, depending on the LA activation pattern before PV ablation. Third, clinical characteristics including the amount of EAT in patients with ECs were assessed.