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.