UF researchers find mental stress increases heart patients' risk of dying

GAINESVILLE, Fla.—Heart disease patients have more to fear than the threat posed by a couch potato lifestyle or high-fat foods such as burgers and fries: Mental stress can markedly decrease blood flow to the heart, hiking their risk of dying three-fold, University of Florida cardiologists reported today (3/25).

“That’s a pretty powerful increase in risk,” said Dr. David S. Sheps, associate chief of cardiovascular medicine at UF’s College of Medicine and the lead author of a paper detailing the research findings, published in the online version of Circulation: Journal of the American Heart Association. “That’s a magnitude of difference similar to that posed by any other major risk factor for heart disease, such as cigarette smoking or high cholesterol.”

Other researchers studying heart disease patients have linked mental stress and psychological factors such as anxiety, depression or anger with a combination of adverse events, including an increased chance of heart attack, hospitalization for chest pain, or the need for bypass surgery or angioplasty. But the UF study, funded by the National Heart, Lung and Blood Institute, was the first to single out an independent association between mental stress and death.

Scientists evaluated 196 patients who participated in the national multicenter Psychophysiological Investigations of Myocardial Ischemia study. Study participants had documented coronary artery disease, and all showed signs of reduced blood flow to the heart upon exercise. Each received a radionuclide angiogram, a test that assesses the heart’s pumping ability and pinpoints abnormalities that occur when blood flow is less than optimal.

The angiogram was repeated during a psychological stress test that required them to speak for five minutes about a hypothetical situation involving a close relative who was being mistreated in a nursing home. The angiogram showed abnormalities in a fifth of the patients; most were women, and more were likely to have diabetes.

Later, researchers contacted study participants or their relatives by telephone and reviewed Social Security records to determine how many had died within five years of the study’s completion.

Most strikingly, they found that patients who’d shown abnormalities during the speech test were three times more likely to die than their counterparts without abnormalities. Of the 17 patients who had died, nearly half had new or worsened abnormalities during the speech test, compared with only 19 percent of the survivors.

Researchers noted that psychological traits, differences in exercise test results, and physical changes during exercise or episodes of mental stress did not distinguish patients who died from those who survived. Accordingly, they concluded that mental stress independently predicted the subsequent risk of death, said Sheps, who also is affiliated with Gainesville’s Malcom Randall Veterans Affairs Medical Center. Researchers did not have the resources to classify deaths by cause, though they speculate that most were cardiac-related, he said.

Mental stress appears to raise heart rate and rapidly hike blood pressure, increasing the heart’s need for oxygen, Sheps said, yet less oxygen is supplied in part because coronary arteries constrict, impeding blood flow.

“I think that with an acute stressor you can have an increase in heart rate that is minor, and you can have a very big increase in blood pressure very quickly, which could lead to clotting problems that could promote an acute coronary syndrome, such as rupture of a plaque or maybe a blood clot that leads to heart attack or sudden death,” he said.

“For people who are under a chronic state of psychologic stress, certain physiologic changes occur that tend to promote atherosclerosis and excessive blood pressure increases, which lead to worsening of disease,” he added.

Mental stress typically occurs in two different forms, Sheps said.

“There is a lot of epidemiologic evidence showing that some psychological traits, like depression and anxiety, are chronic mental stressors and are independent risk factors for cardiac disease, including death,” Sheps said. “We also know there are acute psychological stressors that can affect individuals with coronary disease. For example, consider the Iraqi missile crisis in the early 1990s, when Saddam Hussein was throwing missiles at Israel. The rate of heart attacks went up in Tel Aviv, which is believed to be the result of the psychological stress of that situation. Similarly, it’s known that during certain natural disasters, such as earthquakes, the number of heart attacks tends to go up. So chronic stress and acute stress both can affect disease.”

Future research should aim to confirm the UF findings, which have tremendous implications for heart health, said Sheps, who collaborated with researchers from Johns Hopkins, the University of Maryland, the University of Alabama at Birmingham, the University of North Carolina at Chapel Hill, and Boston’s Brigham and Women’s Hospital, among others.

“We need to learn what can be done to reverse this kind of stress response,” Sheps said. “Can you treat patients in some way to prevent them from having psychological stress-induced ischemia? No. 2, can we develop an easy test that could be used routinely to identify these patients who have three times the death rate of other patients?”