Non-high density lipoprotein cholesterol is the best discriminator of myocardial infarction in young individuals.

Background: Several studies have shown that non-high density lipoprotein (HDL) cholesterol is a strong and independent predictor of cardiovascular events. We investigated whether non-HDL cholesterol can discriminate young individuals with myocardial infarction (MI) from age- and sex-matched controls.

Methods: We conducted a case-control study which included 100 consecutive patients who had survived their first MI before the age of 36 years and 100 age- and sex-matched healthy controls without a history of cardiovascular disease. Cardiovascular risk factors were reported and fasting lipids and apolipoproteins were measured.

Results: Patients with premature MI had significantly higher levels of total cholesterol, low density lipoprotein cholesterol, triglycerides, apolipoprotein B, lipoprotein (a) and non-HDL cholesterol and significantly lower levels of HDL cholesterol and apolipoprotein A. Multivariate logistic regression analysis showed that for every 10mg/dl increase in non-HDL cholesterol levels, the odds of having a MI were increased by 34% after controlling for age, sex, body mass index, presence of hypertension, diabetes and smoking habits. Moreover, participants in the highest tertile of non-HDL cholesterol levels had 28-fold higher odds for having a MI (95% confidence interval, 7.5-104.1), compared to those in the lowest tertile. Finally, discriminant analysis showed that non-HDL cholesterol (lambda-Wilks=0.68) was the strongest discriminator for MI among all studied risk factors while smoking (lambda-Wilks=0.80) was the strongest discriminator for MI among the non-lipid risk factors.

Conclusions: Our study suggests that among conventional lipid and non-lipid risk factors non-HDL cholesterol is the best discriminator to predict the presence of MI in individuals under the age of 36 years.