The overall lifetime risk of heart failure (HF) is similar between men and women, however, there are marked sex differences in the landscape of this condition that are both important and under-recognized. Men are predisposed to HF with reduced ejection fraction (HFrEF), whereas women predominate in HF with preserved ejection fraction (HFpEF). Sex differences are also notable in the penetrance of genetic cardiomyopathies, risk factors, e.g. breast cancer which may be associated with cancer treatment-induced cardiomyopathy, as well as sex-specific conditions such as peripartum cardiomyopathy (PPCM). This review outlines the key sex differences with respect to clinical characteristics, pathophysiology, and therapeutic responses to HF treatments. Finally, we address important differences in the prognosis of HF. A central hypothesis is that the higher risk of HFrEF in men compared to women may be attributable to their predisposition to macrovascular coronary artery disease and myocardial infarction, whereas coronary microvascular dysfunction/endothelial inflammation has been postulated to play a key role in HFpEF and maybe the common link among HF syndromes that women are predisposed to Takotsubo cardiomyopathy, PPCM, and breast cancer radiotherapy-induced cardiomyopathy. Under-pinning current sex disparities in HF, there is a paucity of women recruited to HF clinical trials (20–25% of cohorts) and thus treatment guidelines are predominantly based on male-derived data. Large gaps in knowledge exist in sex-specific mechanisms, optimal drug doses for women and sex-specific criteria for device therapy.

Consistent epidemiological data demonstrate that patients with heart failure with preserved ejection fraction (HFpEF) are more likely to be women than men. Exploring mechanisms behind this sex difference in heart failure epidemiology may enrich the understanding of underlying HFpEF pathophysiology and phenotypes, with the ultimate goal of identifying therapeutic approaches for the broader HFpEF population. In this review we evaluate the influence of sex on the key domains of cardiac structure and function, the systemic and pulmonary circulation, as well as extracardiac factors and comorbidities that may explain the predisposition of women to HFpEF. We highlight the potential role of factors exclusive to or more prevalent in women such as pregnancy, preeclampsia, and iron deficiency. Finally, we discuss existing controversies and gaps in knowledge, as well as the clinical importance of known sex differences in the context of the potential need for sex-specific diagnostic criteria, improved risk stratification models, and targeted therapies.

ObjectiveIron deficiency (ID) has an established impact on outcomes in patients with heart failure with reduced ejection fraction; however, there is a lack of conclusive evidence in patients with heart failure with preserved ejection fraction (HFpEF). We sought to clarify the prevalence and impact of ID in patients with HFpEF.MethodsA systematic search of Cohcrane, MEDLINE, EMBASE, Web of Science and CINAHL electronic databases was performed to identify relevant studies. Included studies defined HFpEF as heart failure with an ejection fraction ≥50%. We used a random-effects meta-analysis to determine the composite prevalence of ID in patients with HFpEF across the included studies. Other outcomes were assessed with qualitative analysis due to a paucity of studies with comparable outcome measures.ResultsThe prevalence of ID in the included studies was 59% (95% CI 52% to 65%). ID was associated with lower VO2 max in three of four studies reporting VO2 max as an outcome measure, lower functional status as determined by dyspnoea class or 6 min walk test in two of three studies, and worse health-related quality of life in both studies reporting on this outcome. Conversely, ID had no impact on death or hospitalisation in three of the four studies investigating this.ConclusionsID is highly prevalent in patients with HFpEF and is associated with worse exercise capacity and functional outcomes, but not hospitalisation or mortality. Our study establishes that ID may play an important a role in HFpEF.