B-PO04-182 CARDIAC RESYNCHRONIZATION THERAPY IN PACING INDUCED CARDIOMYOPATHY - REDUCTION IN QRS 3D VOLTAGE TIME INTEGRAL (3D QRS AREA) PREDICTS ECHOCARDIOGRAPHIC RESPONSE

Abstract

The instantaneous absolute 3D ECG voltage integrated over the duration of the QRS (VTIQRS-3D), also measured as 3D QRS area, is a marker for left ventricular electrical dyssynchrony in patients with left bundle branch block undergoing cardiac resynchronization therapy (CRT). Among patients with pacing induced cardiomyopathy (PICM), we sought to investigate if the reduction in VTIQRS-3D after CRT is associated with improvement in echocardiographic left ventricle ejection fraction (LVEF). We conducted a retrospective study of all CRT upgrades for PICM at our center from 2014 -2018. ECGs were obtained prior to CRT and within 6 months after CRT. 12-lead ECGs were converted to orthogonal X, Y, Z leads using Kors matrix. VTIQRS-3D was obtained by voltage-time-integral from the root-mean-squared 3D ECG. Echocardiograms were obtained prior to CRT and 3-12 months after CRT. We used linear regression models to evaluate predictors of change in LVEF. We included 114 patients (age 74 ± 11 years, 26% female) who underwent CRT upgrade for PICM. Baseline LVEF was 29.2 ± 8.1% and LVEF improved by 14.0 ± 10.5% with CRT. Increase in LVEF was predicted by larger VTIQRS-3D (p=0.03) but not baseline QRS duration (p=0.2). Further, reduction in both QRS duration and VTIQRS-3D with CRT predicted increase in LVEF (both p=0.03), but only reduction in VTIQRS-3D remained statistically significant in multivariable models. In patients with pacing induced cardiomyopathy, a larger reduction in QRS 3D voltage time integral with CRT upgrade independently predicts a greater echocardiographic response.