Effects of physiological levels of estrogen on coronary vasomotor function in postmenopausal women

Abstract

Background: Estrogen replacement therapy has been associated with a reduction in cardiovascular events in postmenopausal women. One of the mechanisms responsible may be a beneficial effect of estrogen on coronary vascular function. We therefore studied the short-term effects of estrogen on coronary artery dimensions and microvascular resistance in postmenopausal women. Methods and Results: Twenty postmenopausal women 61±7 years old participated in this study. Seven had angiographic evidence of atherosclerosis of the left coronary artery. Coronary artery diameters were measured by quantitative coronary angiography. Blood flow velocity was measured with a Doppler wire placed in a proximal left coronary artery segment. Left coronary artery infusions of acetylcholine (range, 10-8 to 10-5 mol/L estimated delivered concentrations) and of adenosine (n = 18) and sodium nitroprusside (n = 10) were performed before and during concomitant continuous intracoronary infusion of 17β-estradiol to test endothelium-dependent and independent vasodilation, respectively. Intracoronary infusion of estradiol increased coronary sinus estradiol levels from postmenopausal (16±11 pg/mL) to premenopausal (282±121 pg/mL) levels. Estradiol did not affect basal coronary artery diameter, blood flow, or resistance. Epicardial coronary artery constriction induced by acetylcholine infusion in the control study (maximum, 10±15% from baseline) was prevented during repeat acetylcholine infusion with concomitant estradiol administration (P