BACKGROUND Outcomes of hospitalized patients with heart failure (HF) and characteristics of advanced HF stage may vary across left ventricular ejection fraction (LVEF) and world regions. OBJECTIVES This study sought to analyze characteristics of hospitalized advanced HF patients across LVEF spectrum, world regions, and country income. METHODS Among 18,553 hospitalized patients with acute HF (7,902 new-onset HF and 10,651 decompensated chronic HF) enrolled in the global registry REPORT-HF (International Registry to Assess Medical Practice With Longitudinal Observation for Treatment of Heart Failure), the authors analyzed characteristics and outcomes of patients with advanced HF, defined as previously diagnosed HF; severe symptoms before current admission (NYHA functional class III/IV); and >= 1 HF-related hospitalization in the preceding 12 months, excluding the current. Differences among hospitalized advanced HF subgroups stratified by LVEF, world region, and country income were examined. RESULTS Among 6,999 patients with decompensated chronic HF and available previous NYHA functional class and HF hospitalization status, 3,397 (48.5%; 18.3% of the total population) had advanced HF. Of these, 44.5% had severely reduced (<= 30%), 34.9% mildly/moderately reduced (31%-49%), and 20.7% preserved (>= 50%) LVEF. Patients from Eastern Europe had the lowest 1-year mortality (23%), whereas those from Southeast Asia had the highest (37%). Patients from lower-middle-income countries were younger, with shorter HF duration and lower comorbidity prevalence, received fewer beta-blockers and HF-devices, and had higher 1-year mortality (34%) than upper-middle-income (26%) or high-income countries (27%; P = 0.018). Adjusted 1-year mortality risk did not differ among LVEF subgroups (all > 0.05), nor did 1-year HF hospitalization rate (P = 0.56). CONCLUSIONS Hospitalized patients with advanced HF and preserved LVEF had similarly adverse outcomes as those with reduced LVEF. Patients from lower-middle-income countries had less implementation of HF therapies and higher-year mortality. (c) 2025 by the American College of Cardiology Foundation.