Prognostic Implications of Left Ventricular Ejection Fraction Improvement in Patients with Heart Failure with Reduced and Mildly Reduced Ejection Fraction.

Objectives: This study aimed to evaluate the prognostic implications and optimal timing for assessing left ventricular ejection fraction (LVEF) trajectory in patients with heart failure (HF) and an LVEF < 50%. Methods: The Taiwan Society of Cardiology HF Registry 2020 is a prospective, multicenter registry of hospitalized HF patients in Taiwan. This study included patients with an LVEF < 50% during their index HF hospitalization, and at least one follow-up echocardiogram within 2 years. HF with improved EF (HFimpEF) was defined as an absolute increase in LVEF > 10% from baseline. The primary endpoints were all-cause mortality and HF hospitalization at 2 years. Predictors of an improvement in LVEF trajectory were also evaluated. Results: A total of 1478 patients were enrolled, with 873 in the HFimpEF group and 605 in the non-HFimpEF group. HFimpEF was associated with a lower risk of mortality (hazard ratio: 0.41 [0.27-0.62], p < 0.001) and reduced HF hospitalizations (8.6% vs. 24.4%, p < 0.001) at 2 years follow-up. Subgroup analysis showed that survival benefits diverged at an LVEF improvement > 10%, emerging as early as 6 months and persisting beyond 12 months. Lower baseline LVEF was paradoxically associated with better survival. Neither maximal guideline-directed medical therapy (GDMT) score nor revascularization correlated with LVEF trajectory. However, HFimpEF patients received higher doses of renin-angiotensin system inhibitors and beta-blockers in the first year. Conclusions: LVEF trajectory at 6 months appears to be a valuable prognostic tool, and higher-dose fundamental HF therapy was more important than achieving a higher overall GDMT score.