Sex-Based Differences in Heart Failure Across the Ejection Fraction Spectrum Phenotyping, and Prognostic and Therapeutic Implications

Objectives
This study assessed sex-related differences in a large cohort of unselected patients with heart failure (HF) across the ejection fraction (EF) spectrum.

Background
Females are under-represented in randomized clinical trials. Potential sex-related differences in HF may question the generalizability of trials.

Methods
In the Swedish Heart Failure Registry population multivariate Cox and logistic regression models were fitted to investigate differences in prognosis, prognostic predictors, and treatments across males and females.

Results
Of 42,987 patients, 37% were females (55% with HF with preserved EF [HFpEF], 39% with HF with mid-range EF [HFmrEF], and 29% with HF with reduced EF [HFrEF]). Females were older and more symptomatic and more likely to have hypertension and kidney disease but less likely to have diabetes and ischemic heart disease. After adjustments, females were more likely to use beta-blockers and digoxin but less likely to receive HF device therapy. Crude mortality/HF hospitalization rates for HFpEF (hazard ratio [HR]: 1.16) and HFmrEF (HR: 1.14) were significantly higher in females but lower in females with HFrEF (HR: 0.95). After adjustments, the risk was significantly lower in females regardless of EF (HR: 0.80 in HFrEF, HR: 0.91 in HFmrEF, and HR: 0.93 in HFpEF). The main sex-related differences in prognostic predictors concerned diabetes in HFrEF and anemia in HFmrEF.

Conclusions
Males and females with HF showed different characteristics across the EF spectrum. Males reported a lower crude risk of mortality/morbidity in HFpEF and HFmrEF but higher risk of HFrEF, although after adjustments, prognosis was better in females regardless of EF. The observed sex-related differences highlight the need for an adequate representation of females in HF randomized controlled trials to improve generalizability.