PATHOPHYSIOLOGY AND TIME-COURSE OF SILENT-MYOCARDIAL-ISCHEMIA DURING MENTAL STRESS - CLINICAL, ANATOMICAL, AND PHYSIOLOGICAL CORRELATES

Objective-To define the prevalence and pathophysiology of myocardial i schaemia induced by mental stress in patients with coronary artery dis ease and exercise inducible ischaemia, and to determine the correlatio n between the severity of coronary artery disease and ischaemia induce d by speech. Design-Prospective cohort study. Setting-Tertiary care ac ademic institution. Patients and protocol-47 patients with coronary ar tery disease and 20 normal controls were studied using standardised ex ercise and mental stress. The ambulatory nuclear vest provided continu ous measures of left ventricular ejection fraction and relative volume changes: an ischaemic response to mental stress was defined as a decr ease in ejection fraction of greater than or equal to 5% for greater t han or equal to 60 s. Severity of coronary artery disease was assessed by the extent of thallium reversibility on exercise testing and the s everity of angiographic disease. Results-23 (49%) of 47 patients with coronary artery disease had an ischaemic response to mental stress whi ch occurred early, was sustained throughout the task and associated wi th an increase in end systolic volume. In contrast, the pattern of lef t ventricular response in the remaining 24 patients (51%) resembled th at in the normal controls. Patients with mental stress induced ischaem ia tended to have greater severity of coronary disease (mean (SD) tota l number of diseased vessels 1.9 (0.8) v 1.4 (0.9), P = 0.07), more fr equent exercise induced angina (17/23 v 7/24, P = 0.003) and lower inc reases in heart rate (36 (11) v 49 (23) beats per min, P = 0.023) and systolic blood pressure (32 (19) v 45 (18) mm Hg, P = 0.03) during exe rcise. Left ventricular responses to speech and exercise were Canada c ompared in the 23 patients with mental stress induced ischaemia: menta l stress was associated with a greater decrease in ejection fraction a t comparable increases in rate pressure product (- 6.5 (6.3)% v 4.7 (1 1.2)%, P = 0.0001). Conclusions-These findings suggest that mental str ess induction of myocardial ischaemia is common in patients with stabl e coronary artery disease. Susceptible patients may have more function ally severe coronary disease. The time course, pattern, and haemodynam ic features of mental stress induced ischaemia suggest a dynamic decre ase in coronary supply.