Short-term anti-ischemic effect of 17 beta-estradiol in postmenopausal women with coronary artery disease

Background Short-term administration of 17 beta-estradiol improves effort-induced myocardial ischemia in female patients with coronary artery disease. 17 beta-Estradiol also has direct and indirect coronary vascular smooth muscle relaxing properties. The aim of the present study was to evaluate the effect of short-term administration of 17 beta-estradiol on pacing-induced myocardial ischemia by means of continuous monitoring of coronary sinus pH in 16 postmenopausal female patients with coronary artery disease. Methods and Results Patients underwent incremental 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 either 17 beta-estradiol (1 mg sublingual, 9 patients) or placebo (sublingual, 7 patients). The time to the onset of myocardial ischemia during pacing was significantly increased by 17 beta-estradiol (mean+/-SD, 254+/-36 versus 298+/-23 seconds; P<.02) but not by placebo (262+/-45 versus 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 protocol. 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 comparable 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% CI, -0.006, 0.0015; P=NS). Conclusions 17 beta-Estradiol reduces the degree 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 hormone and is not due to preconditioning, as evidenced by 1:he absence of improvement after placebo.