Abstract 12722: Cardiac Resynchronization Therapy in Pacing Induced Cardiomyopathy: A Higher Right Ventricle Pacing Percentage Predicts Greater Improvement in Left Ventricle Ejection Fraction

Abstract

Introduction: Cardiac resynchronization therapy (CRT) upgrade is indicated for improvement of cardiac function in patients with chronic right ventricular (RV) pacing burden >40% and heart failure with reduced ejection fraction. It is uncertain whether the CRT response is different among patients with high (≥90%) versus intermediate (<90%) burden of baseline RV pacing. Hypothesis: To assess the impact of baseline RV pacing percent on ECG and echocardiographic response after CRT upgrade for pacing induced cardiomyopathy. Methods: We conducted a retrospective study of all CRT upgrades for pacing induced cardiomyopathy at our hospital from January 2017 to December 2018. Cohorts were grouped by RV pacing burden ≥90% or <90%. QRS duration, left ventricle ejection fraction (LVEF), and left ventricular internal dimension systolic (LVIDs) were assessed at baseline and 3-12 months post CRT upgrade. Results: We included 82 patients (age 74 ± 12 yr., 71% male) who underwent CRT upgrade for pacing induced cardiomyopathy. The RV pacing burden was ≥90% [median 99% (IQR 98-99%)] in 61 patients, and <90% [median 79% (IQR 69-88%)] in 21 patients. There was a trend towards greater reduction in QRS duration in the ≥90% RV pacing group (28 ± 29 ms vs. 22 ± 38 ms, p=0.5). Improvement in LVEF was greater in ≥90% vs. <90% RV pacing group (14.3 ± 10.1% vs. 6.3 ± 10.1%, p=0.003). The association persisted on multivariable adjustment for age, sex and baseline LVEF (p=0.004). There was a trend towards greater % reduction in LVIDs in the ≥90% vs. <90% RV pacing group (6.4 ± 15.5 % vs. 3.9 ± 14.3 %, p=0.5) [Figure]. Conclusions: A higher baseline RV pacing burden predicts a greater improvement in LVEF after CRT upgrade for pacing induced cardiomyopathy.