Effect of Long-term Hormone Replacement Therapy on Coronary Endothelial Function in Postmenopausal Women

To determine the difference in endothelial function between premenopausal and postmenopausal women and to determine whether hormone replacement therapy (HRT) is associated with an improvement in coronary endothelial function. Women undergoing coronary physiology studies for chest pain at the Mayo Clinic in Rochester, Minn, between December 1992 and April 2002 underwent assessment of coronary endothelium-independent and -dependent function with intracoronary administration of adenosine and acetylcholine, respectively. The coronary diameters, coronary blood flows, and coronary velocity reserves were measured. A total of 270 women (89 premenopausal and 181 postmenopausal) participated in the study. Endothelium-dependent coronary blood flow change (baseline to peak flow) in response to acetylcholine (10 −6, 10 −5, and 10 −4 mol/L) was lower in postmenopausal women compared with premenopausal women (39.7% vs 72.9%, P=.03). There was no significant difference between the postmenopausal women receiving and not receiving HRT with regard to percent change in coronary diameter (-21.8% vs -13.9%, P=.15), percent change in coronary blood flow (37.3% vs 42.7%, P=.74), or coronary velocity reserve (2.7 vs 2.7, P=.82). This study shows that the postmenopausal state is associated with a greater abnormality in coronary endothelial function at the level of the microcirculation. Moreover, HRT status was not associated with an improvement in coronary endothelial function in postmenopausal women.