Patients with coronary artery disease (CAD) who have normal exercise- or adenosine-induced stress test results may still develop perfusion deficits when under mental stress, researchers at the University of Florida, Gainesville, report.

Although there have been reports of mental stress causing ischemia in CAD patients with exercise-induced ischemia, the study by Dr. David S. Sheps and colleagues is the first to evaluate the effects of mental stress in CAD patients with normal exercise test results.

"Positive exercise stress tests are related to major narrowing of epicardial coronary arteries," Dr. Sheps told Reuters Health. However, he believes that during mental stress, "patients experience a spasm or decreased blood flow in the smaller vessels related to endothelial dysfunction."

The research team included 21 subjects, between 59 and 80 years old, with major coronary artery stenosis of 50% or more, a history of percutaneous coronary intervention or coronary artery bypass graft, or previous myocardial infarction (MI). They report their findings in the Journal of the American College of Cardiology for March 7.

The patients underwent baseline nuclear imaging and monitoring of heart rate, blood pressure (BP), and electrocardiogram. Antianginal medications were tapered or discontinued 1 day before the mental stress test.

Within the next week, the subjects were given a public speaking task, which the authors call "role playing a real-life hassle scenario." After 2 minutes of preparation, the subjects spoke for 4 minutes in front of several research personnel.

At 1 minute into the speech, the subjects were injected with ^99mTc-sestamibi and hemodynamic and electrocardiographic (ECG) measurements were recorded. Thirty to 45 minutes later, the participants underwent myocardial perfusion imaging.

The authors compared the number and severity of perfusion defects on the nuclear images obtained at baseline with those obtained after the mental stress task. Images were scored according to technetium-99m uptake (0 = normal, 4 = no uptake) in 20 segments.

Six of the subjects demonstrated reversible ischemia, with summed stress scores of 3 or higher on perfusion imaging. The mean number of new or worsening defects was 1.6 in the overall population, and 3.8 in subjects who had new or worsening perfusion defects.

Mental stress also provoked increases in systolic and diastolic BP and heart rate, although there was no relationship between hemodynamic responses and perfusion defects. None of the patients had chest pain or ECG changes during the stressor.

"In this population of patients, we do not know the significance of the mental-stress induced ischemia or whether it is a risk factor for adverse events," the researcher noted. He and his associates will continue to monitor this group of patients over time to determine the prognostic relevance of their findings.

Even if mental stress is a cardiac risk factor, "it's hard to just tell our patients to avoid stress," Dr. Sheps said. "That's why we are also looking at stress reduction programs to reverse it, so it's not necessarily such a dismal situation."