OBJECTIVETo identify the risk factors for acute myocardial infarction (AMI) and summarize the features of coronary angiographic (CAG) findings in young and elderly patients.

METHODSA case-control study was conducted involving 53 young (below 40 years) and 438 elderly (60 years and over) patients with clinical diagnosis of AMI. The differences in the risk factors, clinical characteristics and CAG findings were analyzed between the two groups.

RESULTSCompared with the elderly patients, the risk factors of smoking and positive family history was more frequently found among the young patients, but the rates of hypertension and diabetes were lower. The levels of triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and apolipoprotein B (ApoB) were significantly higher, while high-density lipoprotein cholesterol (HDL-C) lower in the young patients than in the elderly patients. Angiography identified higher incidence of one-vessel disease in the young patients (73.33% vs 25.09%), but the incidence of double-vessel and multi-vessel diseases was more frequent in the elderly patients (11.11% vs 27.49%, and 8.89% vs 47.01%), most commonly compromising the left anterior descending (LAD) coronary artery in both groups. Modified Gensini score of coronary angiography was lower in the young patients (7.69-/+5.23 vs 16.08-/+7.81). Correlation analysis showed that LDL-C (r=0.289, P=0.046) was positively correlated, while HDL-C (r=-0.589, P=0.01), ApoA-I(r=-0.395, P=0.023) were inversely correlated to the angiographic score. Multiple regression analysis showed a significant inverse linear correlation between HDL-C level and coronary artery stenosis.

CONCLUSIONSmoking, metabolic disorders and positive family history are the major risk factors for AMI among individuals below the age of forty, who often have milder coronary artery stenosis than elderly patients. HDL-C variation is significantly correlated to the degree of coronary artery stenosis in young patients with AMI.