Reproducibility of mental stress-induced myocardial ischemia in the Psychophysiological Investigations of Myocardial Ischemia (PIMI).

OBJECTIVE

Many patients with coronary artery disease (CAD) develop myocardial ischemia in response to mental stress. This has been documented both in the natural environment and in the laboratory. However, the reproducibility of laboratory mental stress-induced ischemia has not been investigated.

METHOD

Sixty patients with documented CAD and a positive exercise stress test discontinued cardiac medications and underwent two standardized mental stress tests (a timed Stroop Color-Word test and a public speaking task) in a nuclear cardiology laboratory (Visit 1), and repeated this procedure between 2 and 8 weeks later (Visit 2). Measurements of cardiovascular function and neurohormonal responses were obtained throughout testing, and mood state was assessed before and after testing.

RESULTS

Sixty-eight percent of the 56 patients with detailed radionuclide data from both visits had consistent responses (ie, ischemia either present during both sessions or absent during both) to the Stroop task (kappa = .29, p = .03), 61% had consistent responses to the speech task (kappa = .20, p = .12), and 60% had consistent responses when ischemia was considered present if it occurred during either the Stroop test, the speech task, or both, and absent if it did not occur during either task (kappa = .22, p = .07). Hemodynamic and neuroendocrine responses to the tests were moderately reproducible.

CONCLUSIONS

We conclude that two popular laboratory tests for mental stress-induced myocardial ischemia are modestly reproducible. The relatively low reproducibility is probably influenced by uncertainties in detecting relatively small changes in wall motion, habituation of the patient to repeated exposure to psychological stressors, and physiological differences in threshold for ischemia on different days of testing.