RESUMO
<p><b>OBJECTIVE</b>To study the clinical characteristics of acute myocardial infarction (AMI) among younger adults and to explore the possible mechanisms of early myocardial infarction, combined with the newly discovered risk factors of coronary heart disease.</p><p><b>METHODS</b>Data on comparative analysis to the exposure rates of the risk factors and inducing factors of non-CAD patients with two groups of AMI patients including younger adults group (< or =40 years old) and aged adults group (> or =50 years old). Coronary angiography was applied.</p><p><b>RESULTS</b>There were differences noticed between the frequencies of risk factors of the two AMI groups. In younger adults group the exposure rates of smoking, hyperlipidemia, positive family history, C-reactive protein (CRP) and fibrinogen were markedly higher, while in elderly group the exposure rates of hypertension, smoking, hyperlipidemia, diabetes, CRP, fibrinogen and homocysteine (HCY) were markedly higher (P < 0.05). Although the clustering status of risk factors of the younger adult group was not higher than that of the elderly group. There were obvious inducing factors before the patients were attacked by AMI and the inducing factors inclined to cluster, which had obvious dose-reaction relationships with the occurrence of AMI in young people.</p><p><b>CONCLUSION</b>Early AMI of younger adults might relate to the clustering status of inducing factors. The coexistence of several kinds of inducing factors was resulted in the occurrence of AMI of the atherosclerosis (As) and non-As patients by means of myocardial ischemia accumulation effect.</p>