Acute myocardial infarction in patients aged under 45 years.

Introduction: Coronary artery disease (CAD) becomes an important cause of morbidity and mortality after the age of 45 years.

Objective: To evaluate the epidemiology and clinical features of all patients under 45 years old admitted with myocardial infarction.

Methods: We studied 595 patients admitted with myocardial infarction between January 2000 and December 2002. We analyzed risk factors for CAD, clinical profile, therapeutics and complications (arrhythmic, mechanical and ischemic). The patients were divided into two groups: A--under 45 years old and B-- aged 45 or over.

Results: Group A--56 patients (9.4%); group B--539 patients (90.6 %). There was a higher prevalence of smoking in group A (57% vs. 23.6%; p < 0.01). Hypertension, diabetes and history of CAD were significantly more common in group B. There were no differences in hyperlipidemia (group A: 43% vs. group B: 43.5%). Fibrinolysis was performed in 28 patients (70%) from group A compared to 40 patients (45.9%; p < 0.01) from group B. Use of digitalis and inotropic agents was greater in group B. No differences were found in other pharmacological therapeutics. We found more complications in group B (24% vs. 11%).

Conclusions: There was a higher prevalence of smoking in patients under 45 years old and of hypertension, diabetes and CAD in patients aged over 45. The high rate of hyperlipidemia in both groups highlights the importance of primary prevention. Fibrinolysis was performed more frequently in younger patients. There were more complications in older patients.