Left ventricular, peripheral vascular, and neurohumoral responses to mental stress in normal middle-aged men and women: Reference group for the Psychophysiological Investigations of Myocardial Ischemia (PIMI) study

Background: The normal cardiovascular response to mental stress in middle-aged and older people has not been well characterized. Methods and Results: We studied 29 individuals 45 to 73 years old (15 women, 14 men) who had no coronary risk factors, no history of coronary artery disease, and a negative exercise test. Left ventricular (LV) volumes and global and regional function were assessed by radionuclide ventriculography at rest and during two 5-minute standardized mental stress tasks (simulated public speaking and the Stroop Color-Word Test), administered in random order. A substantial sympathetic response occurred with both mental stress tests, characterized by increases in blood pressure, heart rate-pressure product, cardiac index, and stroke work index and rises in plasma levels of epinephrine and norepinephrine but not β-endorphin or cortisol. Despite this sympathetic response, LV volume increased and ejection fraction (EF) decreased secondary to an increase in afterload. The change in EF during mental stress varied among individuals but was associated positively with changes in LV contractility and negatively with baseline EF and changes in afterload. EF decreased >5% during mental stress in 12 individuals and >8% in 5; 3 developed regional wall motion abnormalities. Conclusions: Mental stress in the laboratory results in a substantial sympathetic response in normal middle-aged and older men and women, but EF commonly falls because of a concomitant rise afterload. These results provide essential age- and sex matched reference data for studies of mental stress induced ischemia in patients with coronary artery disease.