Long Term Outcomes and Predictors of Reverse Remodelling After Cardiac Resynchronization Therapy Upgrade

Background and Objectives: Upgrades to cardiac resynchronization therapy (CRT) account for approximately one quarter of all CRT indications. Although recent clinical trials have demonstrated significant clinical benefits of upgrade procedures, data on the long-term clinical effects of CRT upgrades remain limited. This study aimed to evaluate long-term clinical, echocardiographic, and device-related outcomes after CRT upgrade and to determine predictors of left ventricular reverse remodelling. Materials and Methods: A total of 97 patients underwent CRT upgrade at a tertiary referral centre, including 57 patients upgraded to CRT with pacemaker (CRT-P) and 40 to CRT with defibrillator (CRT-D). Results: During a 5-year follow-up period, 46 patients (47%) died from any cause. Appropriate device therapy was recorded in 13 (33%) CRT-D patients. The composite endpoint of death or time to first appropriate shock occurred in 25 (63%) CRT-D patients compared with 21 (37%) CRT-P patients (p = 0.013). Patients with CRT-P demonstrated a significantly greater improvement in left ventricular ejection fraction (LVEF) than those with CRT-D (15% vs. 9%, p < 0.003). Greater LVEF improvement was observed in patients with non-ischemic compared with ischemic cardiomyopathy (17% vs. 10%, p < 0.01). In multivariable analysis, pacemaker-induced cardiomyopathy (PICMP) was identified as a predictor of left ventricular (LV) reverse remodelling. Conclusions: In this prospective, non-randomized cohort, CRT upgrade was associated with long-term clinical and echocardiographic improvement. Differences observed between CRT-P and CRT-D groups should be interpreted cautiously, as the study was not designed for direct comparison. PICMP was independently associated with LV reverse remodelling.