MYOCARDIAL-ISCHEMIA DURING MENTAL STRESS-TESTING - IS THE MECHANISM DIFFERENT FROM EXERCISE-INDUCED ISCHEMIA

Responses to exercise and mental stress were compared in 20 male patients with stable coronary disease and positive exercise thallium scintigraphy. The ambulatory nuclear VEST provided repeated determinations of left ventricular ejection fraction, relative ventricular volumes, heart rate and 2-lead ECG. These and repeated measurements of blood pressure were obtained throughout a series of mental tasks and a Bruce protocol exercise test. Two mental stress tasks, Math-Stroop and a personally-relevant Speech, produced falls in ejection fraction of 5% in 80% and 85% of subjects respectively. Compared to Bruce exercise, mental stress- induced left ventricular dysfunction was accompanied by smaller increases in rate pressure product. In the 15 subjects with abnormal left ventricular responses to both Math-Stroop and exercise, the magnitude of fall in ejection fraction during Math- Stroop (123%) was comparable to that during stage 2 of Bruce exercise (137%) whereas increases in rate pressure product were 2000 +/- 2500 and 11000 +/- 4200 respectively. In the 17 subjects with abnormal left ventricular responses to both Speech and exercise, comparable falls in ejection fraction of 67% during Speech preparation and 56% during stage 1 exercise were associated with rate pressure product increases of 1800 +/- 1100 and 7500 +/- 2600 respectively. These features suggest a distinctive pathophysiology for mental stress-induced left ventricular dysfunction. Assessment of left ventricular response to mental stress may contribute independent prognostic data in patients with stable coronary disease.