The purpose of this study was to describe the long-term course of left ventricular remodeling induced by cardiac resynchronization therapy (CRT), adjusting for the confounding effect of patient loss due to disease.

Reverse remodeling has been identified as the primary mechanism of improved symptoms and outcome in heart failure patients.

A total of 313 consecutive patients who underwent CRT with available baseline echocardiograms and subsequent clinical and echocardiographic follow-up were included in the analysis. Long-term follow-up included all-cause mortality, heart transplantation, and implantation of a left ventricular assist device. Longitudinal data analysis of left ventricular end-systolic volume index (LVESVi) was performed to adjust for the confounding effect of patient loss during follow-up.

Patients with uneventful survival had a lower baseline LVESVi (Δ = 8.6 ml/m², SE = 4.6 ml/m², p < 0.0001) and a decreased LVESVi by −0.11 ml/m²/day during first 6 months, whereas the LVESVi remained unchanged in patients with adverse events (p < 0.0001). Beyond 6 months, the LVESVi remained unchanged in patients with uneventful survival, whereas the LVESVi continued to increase in those with adverse events at a rate of 0.01 ml/m²/day (p < 0.0001). Predictors of reverse remodeling were nonischemic etiology, female sex, and a wider QRS duration (p < 0.0001, p = 0.014, and p = 0.001, respectively). In the majority of patients, 6 months indicates a break point after which reverse remodeling becomes significantly less pronounced.

CRT patients with uneventful survival show a significant decrease in the LVSVi at 6 months and generally maintain this response in the long term. Those with adverse outcomes are characterized by left ventricular dilation despite CRT.