Public speaking psychological stress has previously been shown to be associated with silent ischemia. To test the hypothesis that psychological stress elevates plasma β-endorphin and that this changes pain threshold, we studied 20 patients with documented CAD and exercise induced ischemia, Following instrumentation and a 30 minute rest period, venous blood samples for β-endorphin were obtained prior to and immediately post psychological stress, Pain threshold was then assessed using a thermal probe technique at baseline and immediately post psychological stress. Patients gave 3 brief speeches lasting a total of 15 minutes about real life hassle situations.BaselinePeak StressSBP (mmHg)138±4180±4HR (Beats/min)65±378±4Double Product9,047±50814,240±844Plasma β-endorphin (pMoI/L)4.3±0.98.3±2p<0.05Pain Threshold (C°)45.0±0.545.4±0.5P=0.18There was a significant positive correlation between pain threshold post stress and β-endorphin post stress (r=0,58, p=0.008)In patients with CAD and exercise induced ischemia 1) public speaking produces psychological stress manifested by increased cardiovascular reactivity 2) public speaking causes an increase in plasma β-endorphin which is significantly correlated with pain thresholds 3) this may explain the predominance of silent ischemia during psychological stress in patients with CAD.