Cardiac resynchronization therapy for pacing induced cardiomyopathy: Role of baseline right ventricular pacing burden

Background: Cardiac resynchronization therapy (CRT) is indicated for patients with heart failure with reduced left ventricular ejection fraction (LVEF) and chronic right ventricular (RV) pacing burden >= 40% (pacing-induced cardiomyopathy, PICM). It is uncertain whether baseline RV pacing burden impacts response to CRT. Methods: We conducted a retrospective study of all CRT upgrades for PICM at our hospital from January 2017 to December 2018. Univariate and multivariable-adjusted changes in LVEF, and echocardiographic response (>= 10% improvement in LVEF) at 3-12 months post-CRT upgrade were compared in those with RV pacing burden >= 90% versus <90%. Results: We included 75 patients (age 74 +/- 11 years, 71% male) who underwent CRT upgrade for PICM. The baseline RV pacing burden was >= 90% in 56 patients (median 99% [IQR 98%-99%]), and <90% in 19 patients (median 79% [IQR 73%-87%]). Improvement in LVEF was greater in those with baseline RV pacing burden >= 90% versus <90% (15.7 +/- 9.3% vs. 7.5 +/- 9.6%, p = .003). Baseline RV pacing burden >= 90% was a strong predictor of an improvement in LVEF >= 10% after CRT upgrade both in univariate and multivariate-adjusted models (p = .005 and .02, respectively). Conclusion: A higher baseline RV pacing burden predicts a greater improvement in LVEF after CRT upgrade for PICM.