814-3 Effect of Estradiol-17β upon Coronary Arterial Reactivity to Acetylcholine in Men with Coronary Artery Disease

Estradiol-17β (E) has been shown to improve exercise-induced myocardial ischemia and reverse acetylcholine (ACh)-induced coronary constriction in female patients with coronary artery disease (CAD). To test this latter effect in men we studied the effect of intracoronary administration of E (2.5μg) in 7 male patients with proven CAD (mean age 52 years). All patients underwent measurements of coronary artery diameter and coronary blood flow at rest, after control infusion and after infusion of ACh 1.6 and 16μg per min, using quantitative angiography and intracoronary Doppler flowmetry. Infusions were performed before and 20 minutes after the intracoronary administration of E. Coronary artery diameter was similar after either control or estradiol-17β (mean ± SD; 2.9±0.6 vs 2.8±0.5mm respectively. P=NS). E had no effect on the ACh-induced coronary constriction (ACh 1.6μg per min; 2.7±0.3 vs 2.7±0.2mm, P=NS; ACh 16μg per min; 2.6±0.3 vs 2.6±03mm, P=NS; post E vs pre E respectively). Likewise, E had no effect on basal coronary blood flow compared to control (77±11 vs 75±10mL/min respectively, P=NS). E had no effect on the ACh-induced changes in coronary blood flow (ACh1.6μg per min; 95±19 vs 90±22 mL/min, P=NS; ACh 16μg per min; 142±27 vs 137±39mL/min, P=NS, post vs pre E respectively)Estradiol-17β does not appearto attenuate acetylcholine-induced coronary constriction nor enhance acetylcholine-induced coronary blood flow in male atherosclerotic coronary arteries in vivo. This is in contrast to the effect of estrogen in menopausal females. This suggests that the coronary vasculature reacts differently to estrogen in males and female