Effect of mental stress on myocardial blood flow and vasomotion in patients with coronary artery disease

In patients with coronary artery disease (CAD), mental stress may provoke i schemic,electrocardiograph changes and abnormalities in regional and global left ventricular function. However, little is known about the underlying m yocardial blood flow response (MBF) in these patients. Methods: We investig ated the hemodynamic, neurohumoral, and myocardial blood flow responses to mental stress in 17 patients with CAD and 17 healthy volunteers of similar age. Mental stress was induced by asking individuals to solve mathematic su btractions in a progressively challenging sequence; MBF was quantified at r est and during mental stress using N-13 ammonia PET. Results: Mental stress induced significant (P < 0.01) and comparable increases in rate-pressure p roduct, measured in beats per minute x mm Hg, in both patients (from 7826 /- 2006 to 10586 +/- 2800) and healthy volunteers (from 8227 +/- 1272 to 10 618 +/- 2468). Comparable increases also occurred in serum epinephrine (58% in patients versus 52% in healthy volunteers) and norepinephrine (22% in p atients versus 27% in healthy volunteers). Although MBF increased in patien ts (from 0.67 +/- 0.15 to 0.77 +/- 0.18 ml/min/g, P < 0.05) and healthy vol unteers (from 0.73 +/- 0.13 to 0.95 +/- 0.22 mL/min/g, P < 0.001), the magn itude of flow increase was smaller in patients (14% +/- 17%) than in health y volunteers (29% +/- 14%) (P = 0.01). The increase in MBF during mental st ress correlated significantly with changes in cardiac work, in healthy volu nteers (r = 0.77; P < 0.001) but not in patients. Conclusion: Despite simil ar increases in cardiac work and comparable sympathetic stimulation in CAD patients and healthy volunteers, CAD patients exhibit an attenuated blood f low response to mental Stress that may contribute to mental stress-induced ischemic episodes in daily life.