Abstract-Pulse pressure, an index of large artery stiffness, has been associated with coronary events. However, mechanisms for this association remain unclear. In this study, we examined the relationship between pulse pressure and the progression of coronary atherosclerosis and the effects of hormone replacement therapy (HRT) on pulse pressure in postmenopausal women with angiographically confirmed coronary disease followed for 3.2 years in the Estrogen Replacement in Atherosclerosis (ERA) trial. In the ERA trial, 309 postmenopausal women (mean age 66Ϯ7 years) with coronary disease were randomized to estrogen, estrogen plus progestin, or placebo, and followed for 3.2 years. Ten standardized epicardial segments were measured for minimal diameter values at baseline and follow-up using quantitative coronary angiography. For this study, mixed-model analysis of covariance was used to: (1) test the association between pulse pressure and change in mean minimum diameter (MMD) adjusted for baseline MMD and (2) the effect of HRT on follow-up pulse pressure. After adjustment for potential confounders, there was a significant graded increase in progression of coronary stenosis with increasing quartiles of baseline pulse pressure (P test for trendϭ0.0001). The progression rate in women with the highest quartile of baseline pulse pressure was 5-fold higher than in women in the lowest quartile (PϽ0.01). In postmenopausal women with coronary disease, increased levels of baseline pulse pressure are associated with subsequent progression of coronary atherosclerosis in postmenopausal women. HRT had no detectable effect on pulse pressure. Key Words: pulse Ⅲ atherosclerosis Ⅲ women P ulse pressure, an index of large artery stiffness, 1 is a significant predictor of coronary artery disease outcomes, including myocardial infarction 2-5 and restenosis after percutaneous coronary intervention. 6 However, the mechanisms underlying this association remain to be elucidated. In animal models, increased aortic stiffness is associated with coronary ischemia 7 and progression of coronary atherosclerosis. 8 In clinical studies, increased pulse pressure (PP) has been associated with atherosclerosis progression in the aorta 9,10 and carotid arteries, 11-14 but its relationship to coronary atherosclerosis progression in humans remains unknown.Any association between PP and coronary atherosclerosis progression in women may be confounded by hormonal status. Studies in healthy postmenopausal women suggest hormone replacement therapy (HRT) use may have favorable effects on large artery compliance. [15][16][17][18] However, these effects may be limited to specific formulations of HRT 17,19 or certain subgroups of women. 19 Furthermore, aging, established atherosclerosis, 20 or concomitant progestin use 21 may attenuate some of the favorable effects of estrogen on vasculature. Additional studies are needed to examine the association of PP with coronary atherosclerosis progression in postmenopausal women and assess the impact of HRT use on PP.In this stu...