A new study appearing in the Jan. 29 issue of Circulation: Journal of the American Heart Association shows that use of hormone replacement therapy (HRT) in postmenopausal women with no coronary risk factors improves blood flow to the heart and may be helpful in preventing heart disease, the leading cause of death in menopausal women in the United States.

Drs. Roxana Campisi, Lauren Nathan, Gautam Chaudhuri and Heinz Schelbert from the departments of Molecular and Medical Pharmacology and Obstetrics and Gynecology, and other colleagues from the UCLA School of Medicine, studied blood flow at rest and during stress to the heart in 54 postmenopausal women, 31 of whom were taking HRT, and in 12 young healthy women who served as controls.

Postmenopausal women not taking HRT (with or without risk factors for coronary artery disease) had abnormal blood flow readings during stress. HRT was found to improve blood flow following stress in postmenopausal women with no coronary artery disease risk factors.

The study showed that the group of postmenopausal women who had no risk factors and took estrogen had a blood flow during stress comparable to that of a 24-year-old woman, indicating estrogen may improve blood flow at times of stress to the heart.

The improvement in blood flow was the same, whether or not women were taking estrogen alone or estrogen plus a progestogen, leading the researchers to conclude that estrogen replacement therapy with or without a progestogen may prevent abnormality of the blood vessels supplying blood to the heart.

This beneficial effect was not observed in postmenopausal women with risk factors for coronary heart disease.

Risk factors include family history of heart disease, high cholesterol, high blood pressure and cigarette use.

“Postmenopausal women not on HRT tend to have decreased blood flow to the heart during stress at a time when there is increased workload for the heart, and this could be detrimental to the heart,” the investigators said. “Our study found that when no coronary risk factors are present, hormone replacement therapy can normalize blood flow to the heart in women during stress, which leads us to believe that HRT may contribute to the prevention of cardiovascular disease in these women.”

The researchers note that the findings of this study are in line with epidemiological studies in which HRT reduced the risk of cardiovascular morbidity in healthy postmenopausal women when compared to those with coronary artery disease. “The study findings may help women and doctors understand the role estrogen may play in the prevention of heart disease,” researchers said.

This study was funded by a grant from the Heart, Lung and Blood Institute of the National Institutes of Health to Dr. Schelbert, who is the principal investigator, and to Drs. Nathan and Chaudhuri, who are co-investigators in the grant.

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