Report on the Lipid Research Clinic trials.

The Lipid Research Clinic Coronary Primary Prevention Trial was a randomized, double-blind, placebo-controlled intervention trial performed in 3806 hypercholesterolaemic (greater than 265 mg dl-1) but asymptomatic men aged 35-59 at entry. The bile acid sequestrant cholestyramine was used to achieve the cholesterol differential in the treatment group. Both groups received a modest low cholesterol-low fat diet. All subjects were followed for at least seven years (mean duration 7.4 years) during which time a mean fall of 8% and 12% in plasma total cholesterol and LDL cholesterol levels respectively relative to levels in placebo controls were achieved and maintained. The cholestyramine group experienced a 19% reduction in risk (P greater than 0.05) of the primary end point-definite coronary heart disease death and/or definite non-fatal myocardial infarction. In addition, the incidence rates for new positive exercise tests, angina, and coronary bypass surgery were all significantly reduced by 25%, 20% and 21%, respectively, in the cholestyramine group. In the treated group, risk reduction was related directly to reduction in total and LDL cholesterol. In a similar but considerably smaller double blind, placebo-controlled, secondary prevention trial where coronary artery lesion change as determined by serial coronary angiography was the end point (The NHLBI Type II Intervention Trial), cholestyramine treatment significantly delayed the progression of atherosclerotic lesions. Plaque progression related directly to both a fall in low density lipoprotein and a rise in high density lipoprotein.