Effects of the selective estrogen receptor modulator, raloxifene, on carotid artery pulsatility index in postmenopausal women

OBJECTIVE: Estrogen replacement therapy after menopause reduces the incidence of arterial disease and cerebrovascular events. The reduced incidence also seems to be due to a positive effect of estrogens on brain blood flow as shown by a decrease in the carotid artery pulsatility index. Raloxifene, a second-generation selective estrogen receptor modulator, has aroused considerable interest because of its tissue-specific agonist-antagonist effect on estrogen receptors. However, there have been no studies on the effect of raloxifene on carotid blood flow after menopause. METHODS: A total of 66 healthy women in postmenopause for more than a year were divided randomly into 2 groups: the first group (n = 33; mean age +/- SD, 53.3 +/- 5.2 years) was treated with raloxifene (one 60-mg capsule per day) for 6 months, and the other group (n = 33; mean age +/- SD, 51.9 +/- 4 years) was untreated. Doppler ultrasonography was used to measure carotid artery pulsatility index (PI) at the beginning of the study and at 2-month intervals. RESULTS: A reduction in carotid artery PI was observed in all patients receiving raloxifene. No significant changes were observed in the control group. The reduction with respect to baseline values was 6.1%(P <.05) after 2 months, 11.2% (P <.05) after 4 months, and 13.2% (P <.05) after 6 months of therapy.The higher the baseline PI, the greater was its reduction after therapy. CONCLUSIONS: After 6 months of therapy, raloxifene induced a reduction in PI similar to that reported after estrogen therapy. The present results further our understanding of the mechanisms by which raloxifene might reduce the incidence of cardiovascular disease in postmenopausal women.