Risk reductions for cardiovascular disease with pravastatin treatment by dyslipidemia phenotype: a post hoc analysis of the MEGA Study.

Background: The beneficial effect of statins for cardiovascular disease (CVD) prevention has been well established. However, the effectiveness among different phenotypes of dyslipidemia has not been confirmed.

Objective: We evaluated the effect of pravastatin on the incidence of CVD in relation to the phenotype of dyslipidemia.

Methods: The MEGA Study evaluated the effect of low-dose pravastatin on primary prevention of CVD in 7832 Japanese patients, who were randomized to diet alone or diet plus pravastatin and followed for more than 5 years. These patients were classified into phenotype IIa (n=5589) and IIb (n=2041) based on the electrophoretic pattern for this post hoc analysis.

Results: In the diet group there was no significant difference in the incidence of coronary heart disease (CHD), stroke, CVD, and total mortality between the two phenotypes. Phenotype IIb patients, compared to phenotype IIa, had lower levels of high-density lipoprotein cholesterol (HDL-C) and a significantly higher incidence of CVD in relation to a low HDL-C level (<47.5mg/dL; p=0.02). Furthermore, pravastatin decreased the relative risk for each major endpoint in both type IIa and type IIb dyslipidemia. Significant risk reductions were observed for CHD by 38% (p=0.04) and CVD by 31% (p=0.02) in type IIa dyslipidemia but not in phenotype IIb.

Conclusion: Pravastatin therapy provided significant risk reductions for CHD and CVD in patients with phenotype IIa dyslipidemia, but not in those with phenotype IIb dyslipidemia.