Sex differences in pharmacological treatment of heart failure: a meta-analysis of randomized trials

Background and Aims: Women remain underrepresented in heart failure (HF) trials, raising concerns about potential undetected sex-specific differences in treatment efficacy. This study assesses sex differences in the primary efficacy endpoint of HF treatments and examines whether the proportion of women enrolled in a trial influences (variations in) treatment effect estimates. Methods: A systematic search was conducted up to 21 March 2025, including randomized controlled trials (RCTs) (≥100 patients) evaluating pharmacological HF treatments vs. placebo or usual care, with clinical events as the primary outcome. Sex differences in the primary outcome were assessed using a random-effects meta-analysis of the reported relative effect measures (REM) and pooled estimates. For key clinical outcomes, meta-regression analyses were performed to examine the association between the proportion of women enrolled and sex differences in REMs, as well as the overall REMs without separating sex. Results: Of 5749 screened publications, 139 RCTs met inclusion criteria, with 292 027 patients (28.1% women). Based on 78 RCTs that reported sex-stratified treatment effects, pooled analysis showed no difference in treatment efficacy between women and men (delta ln[REM] 0.00; 95% confidence interval (CI) −0.04 to 0.03; P = .85; I2 = 4.1%). Meta-regression found no association between the proportion of women and sex differences in REM (78 RCTs, P = .25), overall efficacy (139 RCTs, P = .24), or other clinical outcomes. Conclusions: These findings suggest that pharmacological efficacy in HF does not differ by sex and that historical female underrepresentation in trials is unlikely to have masked important sex differences. Nonetheless, improving sex balance in HF trials remains essential for societal and ethical reasons. © The Author(s) 2026. Published by Oxford University Press on behalf of the European Society of Cardiology. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.