Task-induced ST segment depression, ectopic beats, and autonomic responses in coronary heart disease patients.

The relationship between psychologically induced autonomic responses, ST segment depression, and ectopy was examined in patients with coronary artery disease (CAD) and controls. Both groups underwent a battery of performance tasks and interviews. Performance tasks were selected to yield predictable sympathetic and vagal responses. Autonomic activation in response to stimuli was documented using heart rate, blood pressure, and vascular indices. ST segment depression was observed in a significant portion of the sample. In subjects with CAD, ST segment depression, but not ectopy, was specifically associated with mental arithmetic. In this task, autonomic changes occurred, suggesting beta sympathetic activation. The prevalence of ST segment depression during mental arithmetic declined when a task-inducing brief, phasic vagal activation was combined with the mental arithmetic. Ectopic beats were not associated with a specific task among either patients or controls. The results supported the importance of psychologically induced autonomic response for the precipitation and inhibition of ST segment depression in patients with CAD.