Chen, Yi-ShengYi-ShengChenHuang, Chi-ChengChi-ChengHuangWang, Chun-ChiehChun-ChiehWangChang, Hung-YuHung-YuChangJUEY-JEN HWANGHou, Charles Jia-YinCharles Jia-YinHouChao, Ting-HsingTing-HsingChaoHung, Chung-LiehChung-LiehHungHsia, Chih-PingChih-PingHsiaTzeng, Bing-HsieanBing-HsieanTzengWu, Yen-WenYen-WenWu2026-04-292026-04-292026-01https://www.scopus.com/pages/publications/105029101374https://scholars.lib.ntu.edu.tw/handle/123456789/737620Objectives: 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. Conclusion: 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. © 2026, Republic of China Society of Cardiology. All rights reserved.enGuideline-directed medical therapyHeart failure with improved ejection fractionPrognosisReal-worldTaiwanjournal article10.6515/ACS.202601_42(1).20250714C41608274