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 patie nts with stable coronary disease and positive exercise thallium scinti graphy. The ambulatory nuclear VEST provided repeated determinations o f left ventricular ejection fraction, relative ventricular volumes, he art rate and 2-lead ECG. These and repeated measurements of blood pres sure were obtained throughout a series of mental tasks and a Bruce pro tocol exercise test. Two mental stress tasks, Math-Stroop and a person ally-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 smalle r increases in rate pressure product. In the 15 subjects with abnormal left ventricular responses to both Math-Stroop and exercise, the magn itude of fall in ejection fraction during Math- Stroop (123%) was comp arable to that during stage 2 of Bruce exercise (137%) whereas increas es in rate pressure product were 2000 +/- 2500 and 11000 +/- 4200 resp ectively. 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 ass ociated with rate pressure product increases of 1800 +/- 1100 and 7500 +/- 2600 respectively. These features suggest a distinctive pathophys iology for mental stress-induced left ventricular dysfunction. Assessm ent of left ventricular response to mental stress may contribute indep endent prognostic data in patients with stable coronary disease.