Clinical trials including an update on the Helsinki Heart Study.

The incidence of myocardial infarction (MI), sudden death and other clinical manifestations of coronary heart disease can be reduced by lowering the blood cholesterol level. This is now well established by multiple clinical trials using a variety of interventions including diet and lipid-lowering drugs. Dietary studies in Los Angeles and in Oslo, Norway, have induced a reduction in blood cholesterol of between 10 and 15% with correlated reductions in coronary disease of 20 to 50%. Both niacin and clofibrate in separate cohorts demonstrated a significant reduction in new MI during 5 years of treatment in the Coronary Drug Project. Similar reductions in new MI occurred in the World Health Organization Study with clofibrate. However, in this trial and different from all other trials, mortality in the drug-treatment group actually increased. This finding remains unexplained. In the more recent Lipid Research Clinics Coronary Primary Prevention Trial using the bile acid-binding resin cholestyramine, only a 9% reduction in total cholesterol resulted in a highly significant reduction in the major end points--MI and sudden death--as well as in other secondary end points, including the need for coronary artery bypass graft surgery, ischemic changes on exercise electrocardiography and new-onset angina. Recently, another primary prevention trial using gemfibrozil produced a similar reduction in total cholesterol but a much more significant increase in high-density lipoprotein cholesterol. The reduction in coronary heart disease was in excess of 34% and was strongly related to both low-density lipoprotein cholesterol reduction and high-density lipoprotein elevation. Combination drug studies have produced larger reductions in total cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)