THE EFFECT OF PROGESTAGENS ON THE CAROTID-ARTERY PULSATILITY INDEX INPOSTMENOPAUSAL WOMEN ON ESTROGEN REPLACEMENT THERAPY

Part of the cardioprotective effect of postmenopausal oestrogen replac ement therapy has been attributed to arterial vasodilation. This effec t is partially reversed in the uterine artery by the addition of a pro gestagen. This study was designed to compare the effects of the C21 pr ogestagen, dydrogesterone and the C19 testosterone derivative, norethi sterone on the carotid artery pulsatility index (PI) (thought to repre sent distal impedance to flow) using a randomized double blind cross-o ver trial. The addition of progestagen resulted in a significant incre ase in the carotid artery PI from a median value of 1.67 during the oe strogen only phase to 1.77 (P=0.02) during the combined phase. This tr end was seen with both dydrogesterone and norethisterone, but there wa s no significant differences in the size of the effect caused by eithe r progestagen. The addition of cyclical progestagen to ERT partially a ntagonizes the reduction in the carotid artery PI. (C) 1998 Elsevier S cience Ireland Ltd.