Effect of hormone replacement therapy on atherogenic lipid profile in postmenopausal women

Women develop cardiovascular disease (CVD) approximately 7-10 years later than men, but progress with similar risk after menopause. Recent studies suggest that hormone replacement therapy (HRT) is cardioprotective when initiated early after menopause, but the mechanisms involved are still unclear.

In the current study, we aimed to examine the effects of HRT treatment on the plasma atherogenicity in postmenopausal women. We studied the total lipid profile in blood samples collected in a randomized, double-blinded, placebo controlled clinical trial of women with a history of venous thrombosis (VT), the EVTET study.

One-hundred and forty postmenopausal women <70 years were included in EVTET and randomized either to active treatment (one tablet of 2 mg estradiol and 1 mg norethisterone acetate daily) (n = 71) or placebo (n = 69). Blood samples were taken at baseline and after 3 months and subjected to routine assessment of hemostatic factors and lipids.

Our study show that HRT compared to placebo significantly reduced plasma levels of Lp(a), ApoA1, ApoB, total cholesterol (TC), HDL-C, LDL-C, TC/HDL-C and LDL-C/HDL-C ratio at 3 months. No effect was observed on ApoB/ApoA1 ratio or triglycerides. The change in Lp(a) was significantly and inversely correlated with the change in estradiol (r = -0.32; P = 0.001) and positively correlated to the change in lipids, tissue factor pathway inhibitor activity and antigen, protein C and fibrinogen (r between 0.26 and 0.45, p < 0.01).

In sum, this study confirms a strong effect of HRT on atherogenic lipids with a large reduction in the pro-thrombotic Lp(a), suggesting an overall favorable effect on thrombogenicity after HRT replacement therapy in post-menopausal women at risk of VT.