Lipoprotein predictors of cardiovascular events in statin-treated patients with coronary heart disease. Insights from the Incremental Decrease In End-points Through Aggressive Lipid-lowering Trial (IDEAL).

BACKGROUND: Few studies have looked into the ability of measurements of apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-1) or apoB/apoA-1 to predict new coronary heart disease (CHD) events in patients with CHD on statin treatment.

AIMS: In the IDEAL trial, to compare lipoprotein components to predict CHD events and to what degree differences in those parameters could explain the observed outcome.

METHODS: We compared the ability of treatment with atorvastatin 80 mg/day to that of simvastatin 20-40 mg/day to prevent CHD events in patients with CHD and used Cox regression models to study the relationships between on-treatment levels of lipoprotein components to subsequent major coronary events (MCE).

FINDINGS: Variables related to low-density lipoprotein cholesterol (LDL-C) carried more predictive information than those related to high-density lipoprotein cholesterol (HDL-C), but LDL-C was less predictive than both non-HDL-C and apoB. The ratio of apoB to apoA-1 was most strongly related to MCE. However, for estimating differences in relative risk reduction between the treatment groups, apoB and non-HDL-C were the strongest predictors.

INTERPRETATION: The on-treatment level of apoB/apoA-1 was the strongest predictor of MCE in the pooled patient population, whereas apoB and non-HDL-C were best able to explain the difference in outcome between treatment groups. Measurements of apoB and apoA-1 should be more widely available for routine clinical assessments.