Abstract 11932: Timing of Hormone Replacement Therapy and Coronary Artery Calcium: The Multi Ethnic Study of Atherosclerosis

Introduction: Cardiovascular disease is a leading cause of mortality in post-menopausal women. Although hormone replacement therapy (HRT) is not recommended for prevention of coronary artery disease, recent evidence suggests the timing of HRT may derive different effects on atherosclerosis formation. Hypothesis: We hypothesize that women who are given HRT closer to the onset of menopause will have less coronary artery calcium (CAC). Method: Study participants were 3,174 women from the Multi-Ethnic Study of Atherosclerosis (MESA). Women who had not yet started menopause, had started menopause but not yet started HRT, had started HRT before menopause, or did not report age of menopause and/or starting HRT were excluded. To evaluate the association between presence of CAC and timing of HRT, we used logistic regression with presence of CAC as the response and with timing of HRT as a continuous linear predictor. We also used predefined categories of the timing of HRT as a predictor. Result: Among the 1396 participants who had gone through or were going through menopause and started HRT post-menopause, the prevalence of CAC was 42%, the mean of CAC was 77 (221) Agatston units, and the median was 0 (0-34).The odds of having CAC was 1.06 (95% CI: 1.04, 1.08; p<0.001) times higher for starting HRT 1 year later post-menopause. The odds ratio was 1.03 (1.01, 1.04; p=0.008; N=1358) after adjustment for traditional cardiovascular risk factors, 1.02 (1.00, 1.05; p=0.02; N=1336) after further adjustment for duration of HRT, and 1.01 (0.99, 1.04; p=0.3; N=839) after further adjustment for type of HRT. The mean difference in CAC associated with starting HRT 1 year later post-menopause was 5.1 Agatston units (3.0, 7.2; P<0.0001); the mean difference was smaller and not significantly different from 0 after adjustment for other risk factors. Conclusion: While this study does not provide evidence that the timing of HRT post-menopause is associated with the amount of CAC, it does provide evidence that starting HRT earlier post menopause is associated with lower odds of CAC.