Hormone replacement therapy and distensibility of carotid arteries in postmenopausal women: a randomized, controlled trial.

OBJECTIVES The study objective was to clarify in a randomized, controlled, observer-blind trial whether hormone replacement therapy (HRT) improves elastic properties of the common carotid artery in women with signs of subclinical atherosclerosis, especially in subgroups with increased risk, and whether less progestin enhances the effect. BACKGROUND Previous observational studies have yielded conflicting results on the influence of HRT on central arteries. Some studies reported improvement of distensibility by estrogen alone or in the subgroup of smokers. METHODS A total of 321 postmenopausal women were randomized to 1 mg 17beta-estradiol plus 0.025 mg gestodene for 12 days every month (HRT 1), or 1 mg 17beta-estradiol plus 0.025 mg gestodene for 12 days every third month (HRT 2), or no-HRT, during 48 weeks. In 173 women, distensibility of the common carotid artery was determined before and after therapy by M-mode ultrasound and brachial blood pressure measurement. RESULTS Change of distensibility was small and similar in the three treatment groups. In the subgroup of current smokers, HRT 2 (low progestin) increased distensibility by 32% (HRT 2: 8.2+/-11.7; HRT 1:0.6+/-6.0; no HRT: -1.8+/-6.8 x 10(-3)/kPa, p = 0.025 for no-HRT vs. HRT 2). In the subgroups with elevated blood pressure, high low density lipoprotein (LDL) cholesterol, or high age, no effect of HRT was detected. CONCLUSIONS This randomized intervention study demonstrates that long-term HRT with estrogen and progestin does not substantially influence distensibility of central arteries. Yet, in currently smoking postmenopausal women, HRT with low progestin seems to improve distensibility; this merits further study in a specifically designed trial.