Mapping and Ablation of AEPVR and Endocardial Gap-related PVR
All PVs should be isolated before the observation of PVR. Additional ablation was given if first-pass isolation was not achieved after circumferential ablation. Thereafter, PV potentials was continuously monitored. Acute PVR was defined as recovery of conduction between any PV and extra-PV structures after 5 minutes counted from the time of isolation. For the first isolated ipsilateral PVs, PentaRay catheter was remained in the veins until ½ of the second ablation circle was completed. It was then placed into the contralateral PVs to guide ablation. A minimum of 40-minute waiting period, counted from the isolation time were thereafter arranged for each PV to monitor acute PVR with PentaRay and ablation catheter.
Once acute PVR was observed, activation mapping was performed to distinguish AEPVR from endocardial gap conduction using the standard described previously[10]. AEPVR was defined as acute PVR with the earliest activation site within ablation circle >5mm distant from the lesion, plus the absence of near-field EGMs along the circle. In contrast, endocardial conduction gap was characterized by the earliest activation site at the ablation line (Figure 1). Pace mapping from within the circle was helpful to differentiate AEPVR and far-field potentials[13], and to localize the proximal insertion sites. For patients with suspected AEPVR but in AF rhythm after PV isolation, direct current cardioversion was attempted after additional ablation performed at the discretion of operators, followed by mapping of AEPVRs. Ablation could be performed by targeting the distal insertions of AEPVRs during sinus rhythm or their proximal insertions during PV pacing.
The time from PV isolation to the observation of each AEPVR was recorded. EGMs were measured by two electrophysiologists with average value as the results. The clinical variables, electrophysiologic characteristics and lesion set parameters were analyzed and compared between patients with and without PVR (Control group), so were they compared between patients showing the 2 types of PVR i.e., AEPVR (AEPVR group) and endocardial conduction gap (Gap group). Furthermore, AEPVRs were compared with a group of epicardial PVR confirmed in repeat AF ablation procedures during the same period, which were not present in the index procedure.