[The lipid hypothesis in the etiopathogenesis of ischemic heart disease: confirmations and doubts resulting from primary prevention trials].

Sufficient evidence exists today pointing to the relationship between high levels of plasma cholesterol and coronary atherosclerosis. Up to now, however, the last criterion for validating the aetiopathogenetic relationship between dyslipidemia and CHD, i.e., the demonstration that reduction of plasma cholesterol reduced the formation or progression of the plaque and the incidence of its fatal or non-fatal cardiac and vascular complications, has been lacking. For more than two decades, numerous trials have had this aim in mind but until very recently results have not been substantiated owing to various deficiencies in the method. Before publication of the NHLBI Task Force of Atherosclerosis, eleven major randomised clinical studies based on hypolipidemia interventions were completed. The three studies involving dietetic interventions were considered non-conclusive overall because of the lack of a double-blind factor and of other important epidemiological criteria. Of three pharmacological trials only two involved studies of primary prevention carried out on a population of hypercholesterolaemics. These produced partial results on certain cardiac end-points but not on total deaths and at times not even on deaths from CHD. Multifactorial studies, finally, were even less demonstrative. Taken together, however, the trials based on hypolipidemia interventions point to interesting though not definitive evidence of a reduction in blood cholesterol levels to reduce the incidence and mortality from CHD. According to the NHLBI, many of these studies lacked important features that were codified and suggested for later studies.(ABSTRACT TRUNCATED AT 250 WORDS)