Elevated pain threshold in patients with effort-induced angina pectoris and asymptomatic myocardial ischemia during exercise test.

The purpose of the present study was to analyze the prevalence of asymptomatic (silent) myocardial ischemia during exercise testing among patients with effort-induced angina pectoris, and further, to compare the pain threshold of patients with symptomatic and asymptomatic myocardial ischemia. A group of 26 patients comprised the study. In half of the patients myocardial ischemia during the exercise testing was silent and in one half it was symptomatic. Asymptomatic myocardial ischemia was defined as an asymptomatic ST-segment depression ≥0.1 mV, lasting longer than 60 s during an exercise test. In patients with asymptomatic ischemia the pain thresholds both on toe and finger were significantly higher than in patients with symptomatic ischemia: mean values were 10.1 versus 4.9 mA on the toes, p <0.025, and 8.4 versus 2.5 mA on the fingers, p <0.01. We conclude that asymptomatic myocardial ischemia during exercise test is seen often in patients with angina pectoris and that this may be due to an increased pain threshold.