Comparison of outcomes in ST-elevation myocardial infarction according to age. 
Myocardial infarction constitutes a significant cause of morbidity and mortality.  Its pathophysiology varies according to age; atherosclerosis is the most common cause in older patients while thrombosis or plaque rupture is behind premature MI.  To compare the outcome differences between young (age ≤ 45 years) and older adults (age > 45 years) presenting with STEMI.  This was a retrospective cohort study of patients presenting with STEMI to the Emergency Department of a tertiary care center, between 2008 and 2018.Cases were patients age ≤ 45 and controls were the older population.  Descriptive and bivariate analyses were conducted followed by Logistic regression to identify the outcomes.  107 cases were matched with 214 controls.  Majority of patients were males (93% of cases and controls).  Younger patients were more likely to be smokers (80% vs. 57%, p < 0.001) and with a family history of MI (56% vs. 37%, p = 0.002).  Diabetes, hypertension, dyslipidemia and a previous history of MI were more common among controls, 37%, 60%, 43% and 42% respectively versus 10%, 24%, 36% and 25% in the younger population.  Younger patients had a higher prevalence of single-vessel disease compared to older patients (73% vs. 50%, p = 0.001).  LAD was the most commonly blocked vessel in both groups (71% vs. 64% respectively).  Ejection fraction was within normal range in the majority of controls and cases (63% vs. 56% respectively and 57% vs. 60% respectively).  Premature MI predominantly affects males and the associated risk factors are smoking and family history of MI.  It's characterized by single-vessel disease as compared to older patients.