Very Long-Term Outcomes of Cardiac Resynchronization Therapy in Patients With Ischemic and Nonischemic Cardiomyopathy.

Background: Cardiac resynchronization therapy with defibrillator therapy (CRT-D) has revolutionized the treatment of heart failure with reduced ejection fraction (EF) among a select group of patients with wide QRS. While outcomes in the short- and medium-term post-CRT have been extensively reported, data on very long-term outcomes (10+ years) are limited.

Objectives: The authors aimed to study outcomes of CRT over very long terms of 10+ years.

Methods: We retrospectively reviewed the records of patients who underwent CRT-D at the Mayo Clinic between January 2001 and September 2022. All patients with an EF ≤35%, QRS ≥120 ms, and CRT-D were included in the analysis. The primary endpoint was all-cause mortality. Double matching-propensity matching followed by univariate and multivariable survival analyses-was conducted using accelerated failure models with a log-logistic distribution. Time ratios (TRs) representing the change in survival for a unit increment change in that variable were reported.

Results: Among a matched cohort of 610 patients, post-CRT-D implantation, the average survival was 16.1 years for patients with nonischemic cardiomyopathy (NICM) and 9.1 years for patients with ischemic cardiomyopathy. NICM was associated with increased survival in both univariate (TR: 1.92; P < 0.001) and multivariable (TR: 1.43; P = 0.014) analyses. Other independent predictors of increased survival post-CRT included baseline left bundle branch block morphology, decreasing age, higher left ventricular EF, female gender, and absence of the following comorbidities: atrial fibrillation, type 2 diabetes mellitus, and chronic kidney disease 3 or higher.

Conclusions: Our data suggest that over the very long term (>10 years), patients with NICM had significantly higher survival post-CRT than patients with ischemic cardiomyopathy.