High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study

Background Apolipoprotein B (apoB) and apolipoprotein A-I (apoA-I) are thou ght to be better predictors of acute myocardial infarction than total chole sterol and LDL-cholesterol. We investigated whether apoB and apoA-I are pre dictors of risk of fatal myocardial infarction. We also aimed to establish whether apoB and apoA-I add further information about risk of fatal myocard ial infarction to that obtained with total cholesterol, triglycerides, and LDL-cholesterol. Methods We recruited 175 553 individuals mainly from screening programmes. We measured concentrations of apoB, apoA-I, total cholesterol, and triglyce rides, and calculated apoB/apoA-I ratio and concentrations of LDL-cholester ol and HDL-cholesterol. The relation between death from acute myocardial in farction and initial values for apoB, apoA-I, and the other lipids was exam ined. Findings Mean follow-up was 66.8 months (SD 41.3) for 98 722 men and 64.4 m onths (41.4) for 76 831 women. 864 men and 359 women had fatal myocardial i nfarction. In univariate analyses adjusted for age and in multivariate anal yses adjusted for age, total cholesterol, and triglycerides, the values for apoB and apoB/apoA-I ratio were strongly and positively related to increas ed risk of fatal myocardial infarction in men and in women. ApoA-I was note d 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 regar ded 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 com mon lipid abnormalities, but have normal or low concentrations of LDL-cho l e sterol.