Hormone Replacement Therapy (HRT) has a beneficial impact on cardiovascular health in hypertensive postmenopausal women

May 16 2005

Oral Hormone Replacement Therapy (HRT) seems to have a beneficial impact on cardiovascular health in hypertensive postmenopausal women, researchers reported at the American Society of Hypertension Twentieth Annual Meeting held in San Francisco.

“Hormone Replacement Therapy, often used by women for postmenopausal symptom relief, has gained significant attention recently for studies suggesting an association with cardiovascular risk,” said Karin Manhem, M.D, from the Cardiovascular Institute in Goteborg, Sweden. “Our study seems to suggest a cardiovascular benefit associated with HRT treatment over six months.”

Left ventricular hypertrophy, or enlargement of the muscle mass in the left ventricle of the heart, can cause serious cardiovascular risks such as heart failure, and even death in extreme cases over an extended period of time. High blood pressure, if not controlled, is one of the leading risk factors for the condition, which is often interpreted as clear evidence of target organ damage.

“We know from previous studies that there is a gender difference in prevalence of hypertrophy,” said Dr. Manhem. “As many postmenopausal women take hormone replacement therapy for symptom relief, we wanted to investigate whether the steroid treatment has any influence on the muscle mass of the heart.”

Dr. Manhem and colleagues enrolled 20 postmenopausal women with high blood pressure who were receiving antihypertensive medication. In a randomized order, they either received estrogen plus gestagen for six months and then placebo for six months, or the opposite treatment. Echocardiographic measurements, which can determine changes in left ventricular mass, were taken before the study, after six months of HRT and after six months of placebo.

“Interestingly, both steroid therapy and placebo were associated with a reduction in left ventricle muscle mass,” noted Dr. Manhem. “However, HRT demonstrated greater reduction in the heart muscle mass than the placebo, especially in patients who received HRT in the final six months of the study.”

“Our findings suggest that while controlling blood pressure is critically important in the reduction of left ventricular mass, HRT can have an additive positive effect on this reduction,” she continued. “We believe this may have to do with the hormones’ interactions with the renin-angiotensin-aldosterone system [RAAS], which plays a major role in regulating blood pressure.”

The renin-angiotensin-aldosterone system is a neuroendocrine system that involves the interactions of several molecules that occur naturally within the body. When the body produces too much of an enzyme called renin, the biological interactions that follow increase blood pressure through a variety of mechanisms. Angiotensin-converting enzyme (ACE) inhibitors, and angiotensin-receptor blockers (ARB) are a widely prescribed types of medication that lowers blood pressure by inhibiting steps in the biological processes of the renin-angiotensin-aldosterone system.

Further evaluation of Dr. Manhem’s data showed that women treated with HRT and blood pressure medication that was not blocking the RAAS showed a marked reduction in heart muscle mass over those that were treated with HRT and an ACE inhibitor or an ARB.

“Those treated with hormone replacement therapy and an ACE inhibitor/ARB actually displayed the same reduction as when the women were taking the placebo,” said Dr. Manhem. “This observation
suggests that HRT may play a similar role as ACE inhibitors/ARBs in regulating left ventricular mass.”

“When the renin-angiotensin-aldosterone system was not already blocked by ACE inhibitors/ARBs, the steroid hormones may have interacted with this system and reduced LVH through a mild blockade,” she added.

However, Dr. Manhem warns caution in interpreting the study results due to its small size. “In the twenty women we studied, HRT seems to have a positive effect in reducing left ventricle muscle mass through a mechanism that we believe is related to the renin-angiotensin-aldosterone system. Further and larger studies are needed for more conclusive evidence and we can determine if, when and how women should be treated in clinical practice.”