Long-Term Reverse Remodeling With Cardiac Resynchronization Therapy. Results of Extended Echocardiographic Follow-Up

Objectives: 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. Background: Reverse remodeling has been identified as the primary mechanism of improved symptoms and outcome in heart failure patients. Methods: 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. Results: 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. Conclusions: 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.