Sex Differences in Heart Failure Epidemiology and Clinical Characteristics in Spain: A Nationwide Population-Based Study

Background: Heart failure (HF) is a major public health problem and a paradigmatic condition for sex differences in cardiovascular disease. However, national population-based evidence describing these differences remains limited. We aimed to provide the first nationwide sex-stratified epidemiologic characterization of HF in Spain, quantifying incidence, prevalence, and clinical characteristics across age groups and left ventricular ejection fraction (LVEF) categories. Methods: We conducted a retrospective population-based study using the BIG-PAC database, integrating electronic health records from primary and hospital care covering approximately 1.8 million individuals across seven Spanish autonomous communities. Adult patients with incident HF between 2013 and 2019 were identified. HF phenotypes were classified according to LVEF as reduced (HFrEF ≤40%), mildly reduced (HFmrEF 41–49%), preserved (HFpEF ≥50%), or unknown (HFuEF). Incidence rates per 1000 person-years and prevalence were estimated and stratified by sex and LVEF phenotype. Results: In total, 19,961 incident HF cases were identified. Overall HF incidence was 3.23 per 1000 person-years and was similar in women and men (p = 0.697). HF prevalence was 2.34% and higher in men than in women (2.67% vs. 2.06%; p < 0.001). Women were older and more frequently presented with HFpEF (38%), whereas HFrEF predominated in men (53%); notably, HFrEF still accounted for approximately one third of HF cases among women. Once stratified by LVEF phenotype, clinical characteristics were broadly similar between sexes. Conclusions: While HF incidence was similar in women and men, substantial sex differences in prevalence, age, and phenotype distribution were identified, establishing the first nationwide epidemiological framework to inform sex-aware HF prevention and healthcare planning in Spain.