Anatomical vs. electrophysiological approach for ablation of premature ventricular contractions originating from the left ventricular summit (ISESHIMA-SUMMIT Study).

Aims: Catheter ablation (CA) of idiopathic ventricular arrhythmias (VAs) from the epicardial left ventricular summit is challenging. The endocardial approach targets two sites: the endocardial closest site (ECS) to the epicardial earliest activation site (epi-EAS) and the endocardial earliest activation site (endo-EAS). We aimed to differentiate between cases where CA at the ECS was effective and where CA at the endo-EAS yielded success.

Methods and results: Fifty-eight patients (47 men; age 60 ± 13 years) were analysed with VAs in which the EAS was observed in the coronary venous system (CVS). Overall, VAs were successfully eliminated in 42 (72%) patients: 8 in the CVS, 8 where the ECS matched with the endo-EAS, 11 at the ECS, and 15 at the endo-EAS. A successful ECS ablation was associated with a shorter epi-EAS-ECS distance (10.2 ± 4.7 vs. 18.8 ± 5.3 mm; P < 0.001) and shorter epi-EAS-left main coronary trunk (LMT) ostial distance (20.3 ± 7.6 vs. 30.3 ± 8.4 mm; P = 0.005), with optimal cut-off values of ≤12.6 and ≤24.0 mm, respectively. A successful endo-EAS ablation was associated with an earlier electrogram at the endo-EAS [23 (8, 36) vs. 15 (0, 19) ms preceding the QRS; P < 0.001] and shorter epi-EAS-endo-EAS interval [6 (1, 8) vs. 22 (12, 25) ms; P < 0.001], with optimal cut-off values of ≥18 and ≤9 ms, respectively.

Conclusion: Shorter anatomical distances between the epi-EAS and ECS, and between the epi-EAS and LMT ostium, predict a successful ECS ablation. The prematurity of the endo-EAS electrogram and a shorter interval between the epi-EAS and endo-EAS predicted a successful endo-EAS ablation.