PO-714-07 ELECTROCARDIOGRAPHIC DISCORDANCE TO PREDICT LEFT VENTRICULAR SUMMIT VENTRICULAR ARRHYTHMIA ORIGIN

Abstract

Left ventricular summit region (LVS) ventricular arrhythmias (VAs) can be challenging to eliminate with ablation (Abl) and may be confused for VAs arising from more easily accessible outflow tract (OT) areas. ECG clues are few but important to guide management. We aimed to identify novel ECG discordance patterns to predict LVS VA origin and inform catheter Abl complexity. Consecutive patients 2017-2021 undergoing Abl of LVS VAs (OT VAs with suspected intramural origin based on mapping and need for Abl from >1 sites in right (RV) or left ventricular (LV) OT or great cardiac vein/anterior interventricular vein (GCV/AIV) for VA control) were included. All inferior axis VAs were analyzed on 12-lead ECG. Discordant ECG patterns, or those in which precordial transition and lead I axis were inconsistent with RVOT or LVOT origin, were identified: 1) left bundle, right axis, precordial transition by V3 (LBRI-early), or 2) right bundle, left axis (RBLI). Concordant patterns were those with vectors consistent with either RVOT (LBRI, precordial transition >V3) or LVOT (LBLI, precordial transition V3, or RBRI) exit (Figure). Of 29 patients identified (69% male; mean age 59.0 ± 12.8 yrs; LVEF 43 ± 15%), 16 (55%) had discordant ECGs, most (14/16) with LBRI-early pattern; 13 had concordant ECGs, 3 suggesting RVOT and 10 consistent with LVOT exit. All patients required Abl from multiple anatomic sites, including LVOT in all, RVOT in 10, and GCV/AIV in 7, to effect partial or complete success in 25 (86%) patients after mean 1.9 1.2 Abls. Among discordant ECG patients, Abl at more anatomic sites was necessary to reduce VA burden (Figure). ECG discordance is a marker of ventricular arrhythmias arising from the left ventricular summit region. Identification of this novel ECG feature can improve the ability to predict the site of origin and to guide in ablation of LV summit arrhythmias.