Association of anemia with risk factors in acute heart failure: differences across etiologies and ejection fraction

Background Anemia, as other risk factors or comorbidities in acute heart failure (AHF) patients, remains under-described and underrecognized in Latin America. Purpose To characterize HF patients with anemia enrolled in the RIFACA registry (Registro Colombiano de Falla Cardíaca) and evaluate associated risk factors at hospital admission. Methods RIFACA is a single-center and prospective registry that includes AHF adults (≥18 years) patients treated in a high-complexity institution in Latin America, and started enrolling patients in 2011. This study is a retrospective cohort subanalysis of RIFACA. Anemia is defined as hemoglobin (Hb) levels <13.0 g/dL in men and <12.0 g/dL in women. Sociodemographic, clinical, hemodynamic, and echocardiographic data were collected at admission and reported as means/medians or frequencies. Logistic regression identified independent anemia-associated factors; statistical significance was set at p < 0.05. Results 1,224 adults were included from 2011 until 2024. Median age was 66 years, anemia was present in 44.3% of patients (49.3% mild, 44.3% moderate, 6.5% severe). Ischemic cardiomyopathy (34.6%) was the most frequent etiology, whereas valvular and dilated etiologies were more common among anemic patients (p < 0.001). Hypertension was the most prevalent comorbidity and occurred more often in anemic patients (70.7% vs. 64.8%; p 0,031). NYHA functional class improved overall from admission to discharge (67.8%). In anemic patients, 66,3% improved, 27,2% remained unchanged, and 6.5% deteriorated. Functional worsening was significantly higher among anemic patients [Risk ratio 2.25; 95% CI 1.20–4.20]. In multivariable models, anemia was independently associated with chronic kidney disease [Odds ratio (OR) 1.96; 95% CI 1.36–2.83; p<0.001] and higher serum creatinine (OR 1.41; 95% CI 1.21–1.65; p<0.001), meanwhile lower serum sodium (OR 0.96; 95% CI 0.93–0.99) and left ventricle ejection fraction (LVEF) ≤40% (OR 0.60; 95% CI 0.43–0.83; p 0.002) were inversely associated. Conclusion Anemia affected nearly half of patients and clustered with renal dysfunction, pulmonary congestion, and lower perfusion pressures, delineating a distinct clinical profile. Findings highlight the prognostic relevance of anemia in AHF and support closer risk stratification in this population.