Myocardial tissue characteristics and left ventricular reverse remodeling in non-ischemic dilated cardiomyopathy implemented with ivabradine

Introduction The prognostic relevance of myocardial tissue characterization, including T1 mapping, T2 mapping, and extracellular volume fraction (ECV), has been reported in patients with heart failure with reduced ejection fraction (HFrEF). However, the incremental role of tissue mapping in predicting left ventricular reverse remodeling (LVRR) under up-to-date guideline-directed medical therapy (GDMT), including ivabradine, remains unclear. Methods This retrospective study enrolled 255 sinus rhythm non-ischemic dilated cardiomyopathy (NIDCM) patients (60.0% male, median age 56) from a tertiary center between 2012 and 2021. Of these, 198 (78.0%) underwent CMR at the time of diagnosis. Patients with prior cardiac resynchronization therapy were excluded. LVRR was defined as an absolute ≥10% improvement in left ventricular ejection fraction (LVEF), with a final LVEF ≥40%, at the 1-year follow-up. Results Of the 134 patients analyzed, 52.5% achieved LVRR, with a mean LVEF improvement of 28.0% (from 23.0% to 51.0%) at the 1-year follow-up. CMR (3T, Siemens) analysis revealed elevated mapping values in both LVRR and non-LVRR groups, indicating compromised myocardial substrates. The LVRR group had significantly lower T2 relaxation time (43.0ms vs. 45.0ms, reference =39.6ms) and ECV (28.1% vs. 30.7%, reference=25.7%) compared to the non-LVRR group. Persistent adherence to beta-blockers and ivabradine, along with the four pillars of HF medications, were identified as independent predictors of LVRR, alongside other established factors such as sex, QRS duration, and heart rate. Notably, ECV (OR 0.89, 95% CI 0.82–0.97, p=0.006) remained significantly associated with LVRR after adjusting for beta-blocker and ivabradine use, as well as for ≥50% of the target dose of RAS inhibitor or ARNI. However, the association with T2 relaxation time was no longer significant after adjustment. Conclusion Myocardial tissue characterization, particularly of ECV, offers additional prognostic value in predicting LVRR in NIDCM patients undergoing contemporary GDMT, including ivabradine.