Conjugated estrogens reduce endothelial prostacyclin production and fail to reduce postbypass blood loss

Intravenous conjugated estrogens correct bleeding times and reduce bleeding in uremia, gastrointestinal telangiectasias, and liver disease. One study found a similar benefit in patients undergoing open heart surgery. The mechanism by which conjugated estrogens improve bleeding times is unknown. We report on the effect of estrogens on endothelial prostacyclin production and bleeding in coronary bypass surgery. In a randomized, double-blind trial, 16 male patients undergoing elective coronary artery bypass surgery received four daily infusions of conjugated estrogens (0.6 mg/kg/day) or placebo, preoperatively. Groups were similar with respect to age, preoperative hemostatic profiles, and pump time. Conjugated estrogens significantly reduced greater saphenous vein endothelial prostacyclin production in the estrogen group compared to control subjects. Postoperative blood loss was not reduced, with a trend toward increased blood loss in the treatment group. We have shown that conjugated estrogens reduce endothelial prostacyclin production and fail to reduce blood loss in coronary bypass surgery.