The effect of low dose estrogen on hemodynamic response to stress

Abstract

To compare the effect of low dose oral esterified estrogen to that of placebo and standard doses of conjugated equine estrogens (CEE) on hemodynamic responses at rest and after stress. Eleven healthy post-menopausal women were tested for cardiovascular reactivity (mean arterial pressure [MAP], heart rate, stroke volume, and peripheral vascular resistance) during speech preparation, speech, and computer and paper driven STROOP testing and after a cold pressor stress. The women were tested at baseline and again at 6 months after receiving placebo, 0.3 mg of esterified estrogen or 0.625 mg of CEE. Women’s baseline cardiovascular indices were similar before receiving placebo or low dose esterified or standard doses of conjugated equine estrogen. During stressors, women who received low dose estrogen, when compared to themselves at baseline and to women receiving placebo at 6 months, demonstrated a significant improvement in most hemodynamic responses. Mean arterial pressure at rest increased 2.5 mm Hg in the placebo group, while it declined 4.9 mm Hg and 3.0 mm Hg, respectively, in the esterified and conjugated estrogen groups. During all stressors except the cold pressor test, MAP dropped significantly in the low dose esterified and standard dose conjugated equine estrogen groups. A trend toward decreased vascular resistance was noted in women receiving low dose esterified estrogen, but a significant drop was noted only in women receiving 0.625 mg of CEE. The difference between estrogen groups was not significant. Cardiac index was improved in women receiving estrogen. Stroke volume significantly improved only in women who received low dose esterified estrogen. Low dose esterified estrogen use improved hemodynamic testing to a similar extent as 0.625 mg of CEE in postmenopausal women exposed to mental stressors at 6 months. Given that increased vascular resistance and elevated blood pressure contribute to cardiovascular mortality, it is suggested that even substandard dosages of estrogen might offer protection against cardiovascular disease in postmenopausal women.