Myocardial infarction in men aged 40 years or less: a prospective clinical-angiographic study.

HYPOTHESIS: The study was undertaken to characterize acute myocardial infarction (AMI) in young patients.
METHODS: In all 108 consecutive Mediterranean patients with AMI (102 men and 6 women), aged < or = 40 years, were prospectively included in this study over a period of 6.5 years. Coronary angiography was carried out within the first month and data from these patients with normal or diseased coronary arteries were compared. Clinical features, risk factors, and in-hospital and late morbidity and mortality were evaluated.
RESULTS: Young patients with AMI represent 4.1% of the 2,644 patients admitted because of definite AMI during this period. The most common risk factors were cigarette smoking (94.5%) and hypercholesterolemia (48%). Location of the AMI was anterior in 37%, inferior in 57.5%, and non-Q in 5.5%. A history of previous angina was present in 42.5% of the patients, including all seven patients with previous myocardial infarction (6.5%). However, in 52% of the patients the anginal episodes started in the week prior to the AMI. In-hospital mortality and mortality during a mean follow-up of 41 +/- 23 months were 3.7 and 3.8%, respectively. The Kaplan-Meier actuarial curve assessed on 97 of 104 survivors was 100 and 94% at 1 and 5 years, respectively. Coronary arteries were angiographically normal in 17 (20%) of 87 survivors. Compared with young patients who had obstructive lesions, this subset had a lower age and fewer risk factors, reinfarction (p < 0.05), and late angina (p < 0.01), but development of congestive heart failure and survival were similar in both groups.
CONCLUSION: These data suggest that young patients with AMI are very frequently heavy smokers, have a high incidence of angiographically normal coronary arteries, and that the short- and long-term prognosis is excellent.