Postmenopausal hormone replacement therapy and the vascular wall: epidemiology and clinical studies

The clinical relevance of estrogen's multiple acute and more delayed effects on vascular wall structure and function is incompletely understood. This review attempts to reevaluate epidemiological findings and clinical studies concerning the vascular actions of estrogens and gives implications for strategies in postmenopausal hormone replacement therapy (HRT). There is large evidence from observational studies that HRT reduces the risk of cardiovascular mortality and morbidity in postmenopausal women. However, according to the only large randomized, placebo-controlled, secondary prevention Heart and Estrogen/progestin Replacement Study (HERS), women with prevalent cardiovascular disease (CVD) have increased CVD events within the first year after onset of HRT. The net effects of HRT on atherosclerosis, coagulation, fibrinolysis or the inflammatory response are unproven. Randomized trials of intermediate outcomes reveal that HRT has favorable effects on isolated cardiovascular risk factors, e.g. lipoproteins, carbohydrate metabolism and vasodilatation, but the impact of this effects on clinical endpoints is still not clear. The basis of "evidenced based medicine" is currently not sufficient to provide exact recommendation who will benefit from HRT and who might not. Therefore, the decision about hormone use should consider individual benefit-risk profiles.