Requirements of carina ablation for PV isolation
The results of PV isolation by circumferential ablation are shown in Figure 5. PV isolation was achieved by circumferential ablation alone in 5 of the 12 patients (42%) in the EC group, compared to 27 of 29 patients (93%) in the non-EC group (p < 0.003).
The ablation strategy after circumferential ablation was dependent on the operator. In the first 5 of 7 patients in the EC group in whom PVs were not isolated after circumferential ablation, repetitive electroanatomical mapping revealed the earliest potential at the carina region and we performed ablation at the carina resulting in PV isolation. In the last two patients in the EC group, the earliest activation area in the RA was mapped during pacing from the right inferior PV prior to carina ablation, as shown in Figure 6. The earliest area in the RA was broad, and extensive ablation to the area did not result in PV isolation. Eventually, focal ablation at the carina was required in both cases. In contrast, in 4 of the 29 patients (14%) in the non-EC group in whom PV isolation was not achieved by circumferential ablation, subsequent electroanatomical mapping revealed an anterior gap in 2 patients (7%), and ablation of that gap isolated the PVs. In the remaining 2 patients (7%), subsequent electroanatomical mapping showed no gap in initial lesions and early activation at the carina of the RPV. Additive ablation at the carina was performed and the PVs were isolated.