Sex Differences Among Young Patients With ST-Segment-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis

Background: Female sex is associated with lower incidence of myocardial infarction, especially at younger ages. However, sex differences in mortality and coronary artery disease patterns among young patients with ST-segment-elevation myocardial infarction are not well established. This study evaluated sex differences in in-hospital and 1-year all-cause death and in the extent of coronary artery disease in patients aged ≤45 years with ST-segment-elevation myocardial infarction. Methods: A systematic review (December 9, 2025) was conducted using PubMed, Cochrane, Embase, major cardiology conference proceedings, and ClinicalTrials.gov. Studies comparing sexes for outcomes were included. Non-English publications, abstracts without full text, and studies published before 2010 were excluded. A random-effects meta-analysis was performed, with results presented as relative risks (RR) and 95% CIs. Heterogeneity was assessed using τ and I2, risk of bias using the Risk of Bias in Nonrandomized Studies of Interventions tool. The study was registered on the International Prospective Register of Systematic Reviews. Results: Eleven studies including 738 029 patients with ST-segment-elevation myocardial infarction (22% women) were analyzed. Female sex was associated with higher unadjusted in-hospital (RR, 1.56 [95% CI, 1.40-1.74]; τ=0.04; I2=0%) and 1-year mortality rate (RR, 1.78 [95% CI, 1.50-2.12]; τ=0.00; I2=0%). Women more frequently had single-vessel disease (73% versus 60%; RR, 1.13 [95% CI, 1.03-1.23]; τ=0.07; I2=67%), while men had 2-vessel (23% versus 18%; RR, 0.76 [95% CI, 0.68-0.85]; τ=0.00; I2=0%;) and 3-vessel disease (16% versus 9%; RR, 0.49 [95% CI, 0.27-0.86]; τ=0.41; I2=33%). Conclusions: In young patients with ST-segment-elevation myocardial infarction, female sex is associated with higher unadjusted in-hospital and 1-year death despite less extensive CAD. Further studies adjusting for comorbidities and standardizing CAD definitions are needed.