Carotid artery wall thickness in women treated with hormone replacement therapy

To measure the thickness of the individual layers (externa, media, intima) of the carotid artery in two groups of postmenopausal women.

A high resolution ultrasound (25-MHz Osteoson DIII Minhorst) was used to assess the distal end of the common carotid artery. Forty-six women were on hormone replacement therapy (Premarin 0.625 mg and Norgestrel 1 mg) for more than 1 year. The measurements of the treated group were compared to those of 51 postmenopausal women who acted as controls.

No significant difference between the externa and media layers of both groups of women were noted. The media showed a tendency to be thicker in the treated group. The intima of the untreated group was found to be significantly thicker than that of the treated group (P < 0.05). Significant correlations were found between the layers of the carotid artery especially between the externa and media both mainly composed of connective tissue (Collagen Type I and III and elastin). The media/intima ratio of the treated women was significantly higher than that of the untreated group (P< 0.003).

It is postulated that the changes observed may be due to the effect of oestrogen on connective tissue. These arterial changes induced by hormone replacement therapy may partially explain the cardioprotective effect this treatment has on postmenopausal women. The increased intimal thickness in untreated women compared to treated ones on the other hand would represent the reduction in atheromatous plaque formation in women on oestrogen replacement therapy.