Detection and reproducibility of mental stress-induced myocardial ischemia with Tc-99m sestamibi SPECT in normal and coronary artery disease populations

Abstract

Background: Mental stress-induced ischemia, as detected by radionuclide studies, has yielded reversible ischemia in only 30% to 60% of patients with exercise-induced ischemia. Little is known about the reproducibility of myocardial perfusion imaging in detecting mental stress-induced ischemia. The purpose of this study was to further evaluate the occurrence and reproducibility of mental stress-induced ischemia in patients with coronary artery disease (CAD) and in normal control subjects with a low likelihood of CAD by using sestamibi single photon emission computed tomography (SPECT) imaging.

Methods and results: A total of 40 patients were enrolled in this study: 19 patients with CAD and typical angina or reversible ischemia (positive exercise treadmill study or positive adenosine thallium study) and 21 normal control subjects underwent mental stress testing as well as myocardial perfusion imaging. The subjects were given a speaking task, and SPECT imaging was subsequently performed. Two experienced readers compared mental stress imaging with a resting image using a 20-segment cardiac model. Hemodynamic changes in blood pressure and heart rate with mental stress were also measured in all subjects. Each patient with CAD also underwent repeat mental stress testing and myocardial imaging approximately 2 weeks later. Of the 19 patients with CAD and typical angina or with evidence of reversible ischemia, 16 (84%) demonstrated ischemia with mental stress, as detected by sestamibi SPECT imaging. The mean number of new or worsened perfusion defects attributable to mental stress was 3.5, with a mean severity of 1.7. These results were also reproducible. With repeated mental stress testing and myocardial imaging, 12 of the 16 CAD patients (75%) demonstrated evidence of myocardial ischemia. None of the 21 normal control subjects had evidence of mental stress-induced myocardial ischemia. Mental stress also induced reproducible and significant hemodynamic changes in CAD patients.

Conclusions: In patients with known CAD with typical angina or with evidence of reversible ischemia despite taking medications, mental stress was very effective in inducing myocardial ischemia, as detected by sestamibi SPECT imaging. Mental stress was also found to elicit significant hemodynamic responses. Furthermore, these findings demonstrated good reproducibility.