Significant Differential Effects of Hormone Therapy or Tibolone on Markers of Cardiovascular Disease in Postmenopausal Women

OBJECTIVE: The objective was to compare the effects of tibolone and hormone therapy (HT) on lipid profile, vasodilation, and factors associated with inflammation and hemostasis. METHODS AND RESULTS: Fifty-three women received micronized progesterone (MP, 100 mg) with conjugated equine estrogen (CEE, 0.625 mg) or tibolone (2.5 mg) daily for 2 months, with a 2-month washout period. Compared with HT, tibolone significantly reduced total cholesterol (P<0.001), triglyceride (P<0.001), and HDL cholesterol (P<0.001) levels as well as triglyceride/HDL cholesterol ratios (P<0.001) but not LDL cholesterol levels. Tibolone significantly improved flow-mediated brachial artery dilator response to hyperemia from baseline values (P<0.001) by a magnitude similar to that found with HT (P=0.628). Compared with tibolone, which showed no changes, HT significantly increased high-sensitivity C-reactive protein (hsCRP, P=0.030) and reduced antithrombin III (P<0.001). HT and tibolone significantly increased prothrombin fragment 1+2 (F1+2) from baseline values (P<0.001 and P=0.004, respectively). The effects of HT and tibolone on hsCRP, antithrombin III, and F1+2 were significantly different. HT and tibolone significantly reduced plasma levels of plasminogen activator inhibitor type 1 antigen from baseline levels (P=0.006 and P=0.005, respectively) to a similar degree (P=0.988). CONCLUSIONS: Tibolone significantly improved flow-mediated brachial artery dilator response by a magnitude similar to that found with CEE+MP; however, tibolone did not significantly change hsCRP and antithrombin III, and tibolone increased F1+2 less than did CEE+MP.