DALLAS, March 26 – Mental stress can trigger a lack of blood flow to the heart and increase the risk of death in people with coronary artery disease, researchers report in today’s rapid access Circulation: Journal of the American Heart Association.
“Patients who had ischemia in response to mental stress had a three-fold increase in the risk of death compared to people without mental stress,” says David S. Sheps, M.D., lead author and associate chief of the division of cardiovascular medicine, University of Florida Health Sciences Center, Gainesville. “This adds to a growing body of evidence that links mental stress and bad outcomes in individuals with coronary artery disease.”
Previous studies have shown that reduced blood flow during mental stress tests is linked to significantly higher rates of adverse cardiac events. These studies weren’t designed to detect differences in death rates, however.
Researchers used an imaging test called radionuclide angiography to detect “wall motion” abnormalities in the heart’s pumping during ischemia, which occurs when there is not enough blood flow in the coronary arteries. Radionuclide angiography involves injecting a dye to label red blood cells. This lets researchers view the working heart.
“Wall motion abnormalities are specific markers of ischemia,” Sheps says. “Radionuclide imaging provides us a motion picture of the heart beating. Normally there is a nice symmetrical motion of the heart. With ischemia, certain portions will contract less vigorously or bulge out.”
Mental stress increases oxygen demand because blood pressure and heart rate are elevated, he says. Vascular resistance and coronary artery constriction during mental stress also decrease the blood supply. Psychological factors such as anger or depression didn’t increase the patients’ incidence of death in this study. They have been shown to be risk factors in other studies.
The 196 patients in this study – Psychophysiological Investigations of Myocardial Ischemia (PIMI) – had documented coronary artery disease and exercise-induced ischemia. Patients had a more than 50 percent narrowing in at least one major coronary artery or a previous heart attack. Follow-up was done at 3.5 and 5.2 years.
Patients were excluded if they had a serious noncardiac illness, unstable angina, neurological disease, were unable to discontinue medications that influence cardiac function, or had undergone coronary surgery or angioplasty.
An exercise stress test, radionuclide imaging of the heart and a psychological stress test were conducted at the start of the study. In the psychological stress test patients were asked to talk for five minutes on an assigned topic. The topic required role-playing in which a close relative was being mistreated.
The radionuclide test detected abnormalities in the heart’s pumping ability during the speech test in 20 percent of patients. Patients with abnormalities were more often female (24 percent versus 12 percent) and were more likely to have a history of diabetes (27 percent versus 12 percent).
Patients with wall motion abnormalities during the speech test had a 2.8 times higher death rate than those without abnormalities. All of the 17 deaths were men. Forty percent of those who died had new or worsened abnormalities during the speech test compared with 19 percent of the survivors.
Sheps says further study is needed, since this was not a prospectively designed study. While the study did show increased deaths in people with wall motion abnormalities under mental stress, it was not designed to collect complete data on nonfatal events. There also were no resources to classify deaths by cause, so the researchers analyzed associations with total mortality rather than cardiac death.
He says research should focus on reproducing this finding and searching for an inexpensive technique for myocardial imaging, which would make mental stress testing more attractive for routine clinical use.
“It is important to find out which patients are at risk and to learn ways to tailor treatment to those at risk. It may be that we can alter the lifestyles of people at risk and get them to respond differently to the stress,” he says.
According to the American Heart Association, managing stress makes sense for a person’s overall health, but current data do not yet support specific recommendations using stress management as a therapy for cardiovascular disease.
Co-authors include: Robert P. McMahon, Ph.D.; Lewis Becker, M.D.; Robert M. Carney, Ph.D.; Kenneth E. Freedland, Ph.D.; Jerome D. Cohen, M.D.; David Sheffield, Ph.D.; A. David Goldberg, M.D.; Mark. W. Ketterer, Ph.D.; Carl J. Pepine, M.D.; James M. Raczynski, Ph.D.; Kathleen Light, Ph.D.; David S. Krantz, Ph.D.; Peter H. Stone, M.D.; Genell L. Knatterud, Ph.D.; and Peter G. Kaufmann, Ph.D.
NR02 – 1039 (Circ/RAP/Sheps)
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