Women on HRT have less coronary calcium, stenosis

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

Dr. Yining Wang and colleagues at Peking Union Medical College Hospital evaluated 122 postmenopausal women with ECG-gated 16-slice CT for calcium score and stenosis (greater than 70%). 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 had never taken HRT. Wang reported the study at the 2005 European Congress of Radiology.

The researchers found a significant difference in calcium scores: 29.6 in the HRT group versus 125.8 for the control group. They also found a significant difference in the rate of stenosis: 9.6% in the HRT group versus 24.3% in the control group.

The beneficial effects of HRT include vasodilation and modulation of some vessel components such as lipoproteins and coagulation. But HRT also involves some risks, such as stimulating an inflammatory response.

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

In another study led by Wang, researchers evaluated the image quality of coronary CT angiography. They used a 16-slice scanner to examine 188 patients with suspected coronary artery disease. Patients with heart rates above 65 bpm received beta blockers. All studies were reconstructed into maximum intensity projections and volume-rendered images.

Image quality for the left main, left anterior descending, left circumflex, and right coronary arteries was divided into three categories:

- class I: no motion artifacts;

- class II: mild motion artifacts; and

- class III: severe motion artifacts.

Class I contained 85% of 610 branches; class II, 11%; and class III, 4%. The left main artery had more branches in class I, while the right coronary artery had the fewest. CT density in the origin of the aorta was highest in class I and lowest in class III. Lower heart rates were associated with images in class I, while higher rates were associated with class III. Logistic regression analysis indicated that heart rate and CT density in the root of the aorta have the most significant impact on image quality, Wang said.

Wang recommended nine positions of volume-rendered images to view different parts of the heart, especially the caudal view, which is difficult to achieve in conventional angiography.

Forty-seven patients also underwent conventional angiography, which detected 54 branches (of 180) with over 50% stenosis.

Compared with angiography, the sensitivity and specificity of CTA to identify over 50% stenosis were 93% and 92%, and the positive and negative predictive values 82% and 97%, respectively.