Flow resistance in carotid and middle cerebral arteries in postmenopausal women: a comparative study of tibolone and continuous combined hormone replacement therapy

Abstract

Objective: The study sought to compare the vascular resistance and serum lipids of postmenopausal women assigned to tibolone therapy or continuous combined hormone replacement therapy.Design:This was a 6-month, prospective, single-blind, single-center, randomized study. A total of 50 healthy postmenopausal women were enrolled. At study end, 40 women had completed a 6-month follow-up. The firstgroup (23 subjects) received conjugated equine estrogens (CEE) 0.625 mg/day and medroxyprogesterone acetate (MPA) 5 mg/day. The second group (17 subjects) received tibolone 2.5 mg/day. The pulsatility andresistance indexes of the carotid and middle cerebral arteries, and serum lipid profiles were monitored.Results: Comparisons demonstrated that there were no significant differences betweenthe groups in terms of changes in the pulsatility index (PI) and the resistance index (RI) of the common carotid artery (CCA), internal carotid artery (ICA), and middle cerebral artery (MCA) within thestudy period. Both treatments effectively reduced the total cholesterol level and with no significant differences found between the two regimens. However, in comparing the two groups, we found that high-densitylipoprotein (HDL) cholesterol levels were significantly lower in the tibolone group at either 3 months or 6 months after treatment, whereas a significantly higher triglycerides level was observed in theCEE + MPA group after 3 months of treatment. Low-density lipoprotein (LDL) cholesterol levels indicated no significant differences between the two groups after treatment.Conclusions: Thestudy demonstrated that major neck and cerebral vascular impedance was not influenced significantly by either regimen. Nonetheless, lipid profiles were affected differently by tibolone and by continuouscombined CEE + MPA. However, whether or not these findings might modify cardiovascular risk is still unknown.