Effect of hormone replacement therapy on age-related increase in carotid artery intima-media thickness in postmenopausal women

Abstract

The aim of this study was to determine the changes in carotid artery intima-media thickness as measured by B-mode ultrasound in postmenopausal women receiving hormone replacement therapy (HRT) or not. One hundred and fifty-nine healthy postmenopausal women aged 45–65 years were recruited from our menopause clinic. All the selected women were free of cardio-vascular diseases and had no cardio-vascular risk factors. None of the women were receiving lipid-lowering or antihypertensive drugs. Because carotid artery intima-media thickness was shown to be strongly and positively correlated with age in women aged 55 years and older but not before, women were divided into four groups according to age (<55 vs. ≥55 years) and use of HRT (current users vs. never users). All the treated women received non-oral 17β-estradiol with a non-androgenic progestin and had started HRT within the first year after menopause. Scanning of the right common carotid artery was performed with a B-mode ultrasound imager and thickness of the intima-media complex as well as luminal diameter of the artery were determined using an automated computerized procedure. Within each age group (i.e. <55 or ≥55 years), women had comparable demographic characteristics and only differed by HRT use. Long-term treated women had significantly lower total cholesterol levels than untreated women ( P=0.005). Triglycerides, low-density lipids (LDL)-cholesterol and high-density lipids (HDL)-cholesterol levels, systolic and diastolic blood pressure were not significantly different between users and non-users. In women <55 years, no significant difference in carotid intima-media thickness was found between current users (mean 2.5±1.4 years) and non users. In older women, the mean values of carotid intima-media thickness were significantly smaller in current users (mean 6.9±3.3 years) than in never treated women: 0.50±0.05 versus 0.56±0.07 mm, P<0.0001. Carotid artery intima-media thickness was significantly correlated to age in never users ( r=0.5, P<0.0001) but not in women who were currently receiving HRT ( r=0.2, ns). These findings suggest an apparent protective effect of long-term HRT on age-related thickening of the intima-media of the right common carotid artery. This may contribute to explain the apparent cardio-protective effect of HRT after the menopause.