Mental status and pain perception during stressor tests in patients with coronary artery disease

Asymptomatic myocardial ischaemia is frequently observed in patients with coronary artery disease (CAD), both during daily life and during stressor tests. Psychological mechanisms seem to be involved in the lack of pain during myocardial ischaemia. The aim of this study was to verify in a selected population of CAD patients whether mental status might influence the pain perception during different stressor tests. The study population contained 73 male patients (mean age 52+/-8 years) with stable angina during daily life, reproducible exercise-induced myocardial ischaemia during ergometric stress test (EST) and angiographically documented CAD. All patients underwent cold pressor test (CPT), mental arithmetic stress test (MST), hyperventilation test (HT) and mental stress in association with cold pressor test (combined test, MST + CPT). During the stressor tests, myocardial ischaemia was induced in 15/73 (21%) patients by CPT, in 18/73 (25%) by MST, in 15/73 (21%) by HT and in 19/73 (26%) by MST + CPT. Out of the patients with stressor test-induced myocardial ischaemia, silent ischaemia was observed in 43/73 (59%) during EST, in 10/15 (67%) during CPT, in 16/18 (89%) during MST, in 7/15 (47%) during HT and in all patients during MST+CPT (100%). Among the ischaemic symptomatic patients during stressor tests, the lowest anginal pain intensity was experienced during MST (4.0+/-2.2) and the highest during EST, both at peak exercise and at the ischaemia threshold (6.6+/-2.9 and 5.9+/-2.7, respectively, p<0.05). During MST, the prevalence of silent ischaemia was higher than was observed during the other tests. All study patients remained asymptomatic when myocardial ischaemia was induced by MST + CPT. Even the intensity of CPT induced hand pain was significantly higher during CPT alone than during MST+CPT. These results confirm that mental status may influence pain modulation.