Catheter ablation of left atrial focal tachycardia guided by electroanatomic mapping and new insights into interatrial electrical conduction.

Background Experience in catheter ablation of left atrial (LA) focal tachycardia and information about interatrial electrical connections during LA focal tachycardia are limited. Objectives The purpose of this study was to describe our experience in electroanatomic mapping-guided catheter ablation of LA focal tachycardia and to investigate interatrial electrical connections during LA focal tachycardias. Methods Thirty-three patients undergoing catheter ablation for LA focal tachycardia guided by electroanatomic mapping were reported. Interatrial electrical connections were analyzed in LA focal tachycardias with biatrial electroanatomic maps. Results Of the 35 LA focal tachycardias (cycle length 309 ± 100 ms) mapped, 19 (54%) originated from the pulmonary veins (PVs), 6 (17%) from the mitral annulus, 3 (8.6%) from LA roof, 3 (8.6%) from LA posterior wall, 2 (5.7%) from LA appendage, and 2 (5.7%) from LA septum. Fourteen of the 19 PV tachycardias (74%) were located in proximity to PV ostia. In 14 (7 PV, 7 non-PV) LA focal tachycardias with biatrial electroanatomic maps, posterior right atrium breakthrough sites at the intercaval area were identified in 7 PV tachycardias and 1 non-PV tachycardia. Five of the 7 PV tachycardias used only the posterior breakthrough for interatrial propagation. Procedural success was achieved in 33 of 35 LA focal tachycardias (94%) in 31 patients. During 23 ± 19 months of follow-up, 2 patients (6%) had recurrence of ablated tachycardia, and 3 (10%) developed new LA focal tachycardias. Conclusions The PVs and the mitral annulus were the main sources of LA focal tachycardias. The majority of PV tachycardias originated from PV ostia. A posterior interatrial connection appeared to play a major role in interatrial electrical propagation during PV tachycardias. Electroanatomic mapping facilitated precise localization of LA focal tachycardias and achievement of a high rate of ablation success.