Experimental pain measurement in patients with asymptomatic myocardial ischemia.

Men with substantial coronary heart disease determined angiographically and with reproducible myocardial ischemia were studied. During exercise electrocardiography, 22 patients exhibited significant ST segment depression with concomitant angina pectoris (that is, symptomatic myocardial ischemia) and 20 patients demonstrated significant ST segment depression without any symptoms (that is, asymptomatic myocardial ischemia). No significant differences were found between the patient groups in functional variables, coronary angiographic data or coronary risk factors. In contrast, various experimental pain measures (for example, electrical pain threshold, according to Notermans' method, cold pressor test and tourniquet pain test) yielded significant differences between groups. Results indicate that patients with asymptomatic myocardial ischemia demonstrated significantly higher electrical pain thresholds and ischemic pain thresholds, as well as more tolerance to cold and ischemia, so that individual differences in sensibility to pain may partly explain lack of pain in patients with asymptomatic myocardial ischemia.