Insulin-like growth factors and coronary heart disease.

Insulin-like growth factor-1 (IGF-I), the primary mediator of growth hormone (GH) effects, is an important regulator of cell growth, differentiation, and apoptosis. GH and IGF-I deficiency is known to be associated with premature atherosclerosis and elevated cardiovascular disease mortality. Recent evidence suggests that cardiovascular disease risk may also be elevated among apparently healthy individuals who have serum IGF-I levels in the low-normal range. In this review, we appraise the epidemiologic and clinical studies implicating low IGF-I level as a risk factor for incident myocardial infarction and other manifestations of coronary heart disease. Potential mechanisms that may underlie this association include beneficial effects of IGF-I on myocyte survival after ischemia, stability of atherosclerotic lesions, and endothelial function. We conclude that additional confirmatory data from prospective studies are needed to confirm low IGF-I level as an independent cardiovascular risk factor. However, if this finding is confirmed, this would support the rationale for intervention trials aimed at reducing cardiovascular disease morbidity and mortality among older adults by targeting the GH/IGF-I pathway.