SHORT-TERM ANTIISCHEMIC EFFECT OF 17-BETA-ESTRADIOL IN POSTMENOPAUSALWOMEN WITH CORONARY-ARTERY DISEASE

Background Short-term administration of 17 beta-estradiol improves eff ort-induced myocardial ischemia in female patients with coronary arter y disease. 17 beta-Estradiol also has direct and indirect coronary vas cular smooth muscle relaxing properties. The aim of the present study was to evaluate the effect of short-term administration of 17 beta-est radiol on pacing-induced myocardial ischemia by means of continuous mo nitoring of coronary sinus pH in 16 postmenopausal female patients wit h coronary artery disease. Methods and Results Patients underwent incr emental atrial pacing starting at a rate of 100 bpm and increments of 20 bpm every 2 minutes up to 160 bpm before and 20 minutes after eithe r 17 beta-estradiol (1 mg sublingual, 9 patients) or placebo (sublingu al, 7 patients). The time to the onset of myocardial ischemia during p acing was significantly increased by 17 beta-estradiol (mean+/-SD, 254 +/-36 versus 298+/-23 seconds; P<.02) but not by placebo (262+/-45 ver sus 256+/-34 seconds; P=NS) The pH shift was significantly reduced by 17 beta-estradiol but not by placebo at every step of the pacing proto col. The maximum pH shift at peak pacing was significantly I educed by the administration of 17 beta-estradiol by 0.022 pH units (95% CI, 0. 001, 0.043; P<.04) but not by sublingual placebo (-0.002 pH units; 95% (CI, -0.0073, 0.0021; P=NS). The maximum pH shift at maximum comparab le pacing was also reduced by 17 beta-estradiol by 0.015 pH units (95% CI, 0.012, 0.017; P<.001) but not by placebo (-0.0022 pH units; 95% C I, -0.006, 0.0015; P=NS). Conclusions 17 beta-Estradiol reduces the de gree of pacing induced myocardial ischemia in postmenopausal patients with coronary artery disease. The reduction of pacing-induced coronary sinus pH shift is consistent with an anti-ischemic effect of 1:he hor mone and is not due to preconditioning, as evidenced by 1:he absence o f improvement after placebo.