Data on the clinical profile and outcomes of younger patients with ST-elevation myocardial infarction (STEMI) is scarce. This study compared clinical characteristics and outcomes between patients aged<45 years and those aged ≥ 45 years with STEMI managed by the acute myocardial infarction code (AMI Code) network. Sex-based differences in the younger cohort were also analyzed.

This multicenter study collected individual data from the Catalonian AMI Code network. Between 2015 and 2020, we enrolled patients with an admission diagnosis of STEMI. Primary endpoints were all-cause mortality within 30 days, 1 year, and 2 years.

Overall, 18 933 patients (23% female) were enrolled. Of them, 1403 participants (7.4%) were aged<45 years. Younger patients with STEMI were more frequently smokers (P<.001) and presented with cardiac arrest and TIMI flow 0 before pPCI (P<.05), but the time from first medical contact to wire crossing was shorter than in the older group (P<.05). All-cause mortality rates were lower in patients aged<45 years (P<.001). Among younger patients, cardiogenic shock was most prevalent in women than in their male counterparts (P=.002), with the time from symptom onset to reperfusion being longer (P<.05). Compared with men aged<45 years, younger women were less likely to undergo pPCI (P=.004).

Despite showing high-risk features on admission, young patients exhibit better outcomes than older patients. Differences in ischemia times and treatment were observed between men and women.