Distribution and EGM Characteristics of AEPVR
Distal Insertion sites of AEPVR were found 12.8±3.6mm distant from the linear lesion (Right PVs: 12.6±3.5mm, Left PVs: 13.3±4.2mm). They were most frequently located at the posterior PV antrum between the ipsilateral PVs (17/32), including 9 from left and 8 from the right PVs, followed by the anterior (12/32) carina of right PVs. In addition, 2 patients showed epicardial connection at anterior and posterior roof in right PV, respectively. The other one demonstrated acute reconnection to the left PVs through the vein of Marshall (Figure 3). Localized distal activation patten was seen in 25/32 (78.1%) patients, followed by widely spread pattern in the others. In 19/32 (59.4%) cases, activation due to AEPVR propagated into both upper and lower PVs during sinus rhythm. In the rest patients, residual potentials could only be observed in a single PV.
Pace mapping discovered 2 major reconnection patterns. AEPVRs found at the posterior PV antrum were connected to the posterior wall of the left atrium. The connections traversed the ablation line generally in an oblique direction. The connections to right anterior carina showed proximal ends at posterior right atrium presumably through the intercaval bundle (ICB). Different from posterior AEPVR, those connections did not pass the prior ablation line (Supplementary Figure 1). Proximal insertion sites could also demonstrate localized or diffuse patterns (Figure 4).
The EGMs at distal insertion sites of AEPVR showed an amplitude of 0.48±0.38 mV and duration of 26.3±10.0ms without fractionation. The mean slope of major deflection was 0.10±0.09mV/ms. AEPVRs at the anterior carina and posterior PV antrum were similar in amplitude (0.55±0.48mV vs. 0.43±0.28mV, P =0.346) and slope (0.12±0.11mV/ms vs. 0.10±0.09mV/ms, P =0.524). Those distribution and EGM characteristics of AEPVRs did not show difference from the delayed epicardial connection in the repeated ablation procedures (Table 2, Figure 3). In contrast, reconnection owing to endocardial gap conduction was distributed in a wide area along the circular lesion including the left atrial roof, floor and ridge. Most of the EGMs at the reconnection sites involved highly fractionated deflections (Figure 1&3).