Lenzi, M

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 I 2 , 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; I 2 =0%) and 1‐year mortality rate (RR, 1.78 [95% CI, 1.50–2.12]; τ=0.00; I 2 =0%). Women more frequently had single‐vessel disease (73% versus 60%; RR, 1.13 [95% CI, 1.03–1.23]; τ=0.07; I 2 =67%), while men had 2‐vessel (23% versus 18%; RR, 0.76 [95% CI, 0.68–0.85]; τ=0.00; I 2 =0%;) and 3‐vessel disease (16% versus 9%; RR, 0.49 [95% CI, 0.27–0.86]; τ=0.41; I 2 =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.