Coronary artery calcium and bone mineral density by serial CTA: Does menopausal hormone therapy modify the association?

INTRODUCTION: Both osteoporosis and cardiovascular disease (CVD) increase in women after menopause. Estrogen deficiency is thought to be an underlying mechanism for both these conditions. METHODS: Healthy menopausal women (n = 374, age 42-58 years) underwent cardiac CT scans over four years as participants in the Kronos Early Estrogen Prevention Study (KEEPS), a randomized, controlled trial to Women randomized to either oral conjugated equine estrogens (o-CEE, n = 104), transdermal 17ß-estradiol (t-E2, n = 119) or placebo (n-115). CAC (Agatston units, AU), and BMD (mg/cm3) were measured from thoracic vertebrae at baseline and at the 4 years of the study using validated software. ANOVA and multiple linear regression analyzed the association between incident CAC or progression of CAC and BMD among the treatment groups. RESULTS: At baseline 374 women, 40 participants with CAC >0 had greater decrements in BMD than the 334 participants with CAC = 0 at baseline, The average change in BMD in o-CEE group with CAC was -9.6 ± 13.3 versus -3.1 ± 19.5 in those with zero CAC, p = 0.0018. With t-E2, BMD changed by -11.7 ± 26.2 in those with CAC versus +5.7 ± 26.2 in the zero CAC group, p ≤ 0. 0001. Similarly in the 66 participants that showed progression of CAC >1, had more BMD loss, than those with stable CAC regardless of the treatment. CONCLUSION: Progression of bone loss is reduced among women treated with o-CEE or t-E2. Progression of CAC is associated with greater BMD loss, a relationship that is differentially modified by t-E2 and o-CEE.