Acute Myocardial Infarction in Young Japanese Adults : A Large-scale Cohort Study of Acute Myocardial Infarction in Japan (HIJAMI Registry)

Purpose: To clarify the clinical features and in-hospital outcome in young adults with acute myocardial infarctions (AMIs) in Japan. Methods: Between January 1999 and June 2001, we consecutively registered 3,021 patients with AMIs who were admitted to 17 participating medical institutions. The baseline characteristics, risk factors, angiographic findings, initial therapeutic modalities and in-hospital outcomes were retrospectively compared between 122 young patients (≦45 years old; young group) and 2,899 non-young patients (>45 years old; non-young group). Results: The young group represented 4.1% of all AMI patients, and 93.4% were male. The young group had a higher prevalence of hypercholesterolemia and being current smokers. However, the young group was less likely to have a history of hypertension and diabetes. The coronary angiographic findings demonstrated a lower incidence of multi-vessel coronary artery disease in the young group. The young group underwent early reperfusion therapy more frequently than the non-young group. In-hospital morbidity (20.5%) and mortality (1.6%) were significantly lower in the young group than non-young group. Conclusions: Young AMI patients have a different background clinical picture than non-young AMI Japanese patients. They are treated aggressively with acute reperfusion therapy more frequently, and have a favorable prognosis in comparison to non-young AMI patients