Introduction: Acute coronary syndrome (ACS), including acute ST-segment elevation myocardial infarction (STEMI), is more prevalent in older patients (pts), leading to fewer studies with young pts. (1) The age limit varies among studies, but a cut-off of 45 years (yr.) is the most common. Traditional differences described in the risk factors for younger compared to older pts. include a higher prevalence of smoking, family history of premature coronary heart disease (FH) and male gender.

Patients and Methods: We performed a retrospective analysis of medical records of 164 pts. (mean age 43.9±6.5 yr.) hospitalized with STEMI at the University Hospital Centre Zagreb from January 2012 to October 2018, with a cut-off at 45 yr. for men (n=102) and 55 yr. (n=62) for women. Analyzed variables are listed in Table 1. Body mass index (BMI, kg/m²) was interpreted as: ≤18.5 (underweight), 18.6–24.9 (normal), 25.0–29.9 (overweight), ≥30 (obese). Positive cardiovascular FH was defined as relatives with ACS, stable coronary artery disease (SCAD) or cerebrovascular disease.

Results: As seen in Table 1, the majority of pts. were male (62.2%), had a high BMI (n=119; 76.8%), and were current smokers rather than former or non-smokers (78.1% vs 5.6% and 16.3%). The majority of pts. had positive FH (53.7%), whereas the minority had arterial hypertension (49.4%), diabetes mellitus (DM; 7.4%) and a thyroid condition (4.9%). In-hospital mortality was 0.6% (n=1), while 10.4% of pts. (n=17) required rehospitalization (rehosp.). The vast majority of rehosp. were due to ACS (64.7%), followed by SCAD (11.8%), arrhythmias (11.8%), heart failure (5.9%) and other causes (5.9%). A significant correlation was found between the need for rehosp. and the length of stay during hospitalization for the initial STEMI (OR=1.105, p=0.01), as well as with insulin-treated DM (OR=22.873, p=0.01).

Conclusion: The most prominent risk factors in the studied population of young STEMI pts. were smoking, increased BMI and male gender. Roughly one out of ten pts. required rehosp., largely due to ACS, which mostly occurred in pts. with longer initial hospitalization lengths or those on insulin therapy. In-hospital mortality was noted in only one patient.