Background: Apolipoprotein B (apoB) and apolipoprotein A-I (apoA-I) are thought to be better predictors of acute myocardial infarction than total cholesterol and LDL-cholesterol. We investigated whether apoB and apoA-I are predictors of risk of fatal myocardial infarction. We also aimed to establish whether apoB and apoA-I add further information about risk of fatal myocardial infarction to that obtained with total cholesterol, triglycerides, and LDL-cholesterol.
Methods: We recruited 175553 individuals mainly from screening programmes. We measured concentrations of apoB, apoA-I, total cholesterol, and triglycerides, and calculated apoB/apoA-I ratio and concentrations of LDL-cholesterol and HDL-cholesterol. The relation between death from acute myocardial infarction and initial values for apoB, apoA-I, and the other lipids was examined.
Findings: Mean follow-up was 66.8 months (SD 41.3) for 98722 men and 64.4 months (41.4) for 76831 women. 864 men and 359 women had fatal myocardial infarction. In univariate analyses adjusted for age and in multivariate analyses adjusted for age, total cholesterol, and triglycerides, the values for apoB and apoB/apoA-I ratio were strongly and positively related to increased risk of fatal myocardial infarction in men and in women. ApoA-I was noted to be protective. In multivariate analysis, apoB was a stronger predictor of risk than LDL-cholesterol in both sexes.
Interpretation: Although LDL-cholesterol and HDL-cholesterol are known risk factors, we suggest that apoB, apoB/apoA-I, and apoA-I should also be regarded as highly predictive in evaluation of cardiac risk. Although increased throughout the range of values of LDL-cholesterol, apoB and apoA-I might be of greatest value in diagnosis and treatment in men and women who have common lipid abnormalities, but have normal or low concentrations of LDL-cholesterol.