Background and aim: Studies of young patients with acute myocardial infarction (AMI) have demonstrated that conventional risk factors are usually responsible for their premature atherosclerosis. No account has yet been published of the risk profile of young Italians surviving an AMI. In this study, the conventional risk factors, lipids and apolipoproteins, and apolipoprotein E (APOE) allele distribution were evaluated in 98 consecutive AMI survivors (94 males, 4 females) aged 40.1 +/- 3.9 for at least three months after their acute event. These survivors were matched for age, sex, body mass index and presence of diabetes mellitus with 98 controls selected from subjects admitted to the same hospital for other reasons.
Methods and results: Lipid profiles and APOE polymorphism were determined in both groups. Coronary angiography during hospitalization showed the absence of critical stenosis in 6.6% of the survivors, mono-vessel disease in 57.7%, and multi-vessel disease in 35.5%. The survivors had a higher frequency of smoking, hypertension, family history for coronary artery disease (CAD) and dyslipidemia, and a much greater frequency of 3 or more risk factors than the controls: Odd ratios (OR) 7.4, 95% confidence interval (CI) 2.5-18.6, p = 0.0000. Significant differences were found between the groups for triglycerides (p = 0.000002), total cholesterol (p = 0.003), LDL-cholesterol (p = 0.012), HDL-cholesterol (p = 0.0002), apolipoprotein AI (p = 0.00001), and Apolipoprotein B (p = 0.000001). No differences were observed in APOE allele distribution (APOE*4 0.11 vs 0.08, APOE*3 0.86 vs 0.89, APOE*2 0.03 vs 0.03), nor in lipid profile when both higher risk genotype (E3/4, E4/4, E2/4) and lower risk genotype groups (E2/2, E2/3, E3/3) were analysed. OR were calculated as measures of the association of the E4-positive genotypes with AMI. They indicated a non-significant increase in risk of AMI when the survivors were compared with the controls (OR 1.78, 95% CI 0.84-3.70, p = 0.13).
Conclusions: This study provides further evidence that conventional coronary risk factors are usually present in young AMI patients. The APOE*4 allele was associated with a 1.8 non-significant increase in the risk of AMI in our group with premature CAD. Comparison with controls showed that the presence of three or more risk factors sharply increased the probability of premature CAD and that hyper-triglyceridemia is an independent risk factor. The data on APOE polymorphism are less certain and a larger study is needed.