Hormone replacement therapy reduces coronary artery disease

Hormone replacement therapy is known to carry a risk of cardiovascular events. Researchers in China, however, have found that women taking HRT have significantly lower coronary calcium scores and significantly less coronary artery stenosis. They recommend cutting the standard HRT dosage by half so women can retain the positive benefits against osteoporosis, as well as reduce the risk for coronary heart disease.

Dr. Yaning Wang and colleagues from Peking Union Medical College Hospital evaluated 122 postmenopausal women with ECG-gated 16-slice CT. The women, all faculty members at the hospital, were divided into two groups: 54 who had taken HRT for more than five years, and 75 who never took HRT.

The researchers performed unenhanced scans to score calcium (three subjects with coronary stents didn't have calcium scores) and contrast-enhanced scans to determine stenosis (greater than 70% was considered severe).

The mean calcium score of the HRT group was 29.6, compared with 125.8 for the control group. The difference was significant, Wang said.

A similar significant difference was found in the incidence of stenosis. The HRT group had a rate of 9.6%, while the control group's rate was 24.3%. Logistic regression found that HRT had a significant effect on coronary stenoses over 70%, she said.

The beneficial effects of HRT include vasodilation and modulation of some vessel components such as lipoproteins, coagulation, and the fibrinolytic factors. But HRT also has some risks, such as stimulating an inflammatory response. Additionally, progesterone, which is prescribed in combination with estrogen, could diminish the beneficial effect of estrogen.

Studies have shown that at a lower concentration, estrogen is more effective in vasodilation, inhibiting tissue factor expression, and resisting the inhibiting factor of progesterone. But at higher concentrations the beneficial effects are not apparent, Wang said.

"The cardiovascular risk from HRT remains controversial. It is urgent that we find the right dosage that could retain HRT's beneficial affect and reduce the cardiovascular risk," she said.

An audience member questioned whether the study was biased because the selected population could have been at a higher risk for heart disease. Wang said that they found no significant differences between the two groups regarding body mass index, hypertension, and smoking and drinking history.