Some Heart Patients Vulnerable to Mental Stress

The fear of public speaking might cause some people to do more than just break out in a cold sweat and battle stomach-churning butterflies - it could prove to have consequences for their heart health.

University of Florida cardiologists have identified a group of heart disease patients who appear especially vulnerable to the physical effects of mental stress.

Chronic anxiety, depression or anger are widely recognized as raising the risk of heart attack, hospitalization or sudden death in patients whose hearts suffer dangerous decreases in blood flow during exercise testing. Even something as simple as public speaking, doing mental arithmetic or recounting an argument with a loved one can trigger a problem.

But until now, patients who trod the treadmill without experiencing chest pain or restricted blood flow had never been similarly scrutinized when it came to mental stress. Yet what goes on in their heads could have consequences for their hearts as well, UF researchers write in today's (March 7) issue of the Journal of the American College of Cardiology. A third of the heart patients they studied developed temporary changes in heart rhythm or restricted blood flow when they were asked to role-play a difficult interpersonal situation, even though their hearts responded normally to exercise.

"Recently our group and some other investigators have started to expand the population of patients that we're looking at to try to explore what happens when mental stress is applied," said David S. Sheps, M.D., a professor and associate chairman of cardiovascular medicine at UF's College of Medicine and the Malcom Randall Veterans Affairs Medical Center. "We believe the phenomenon of mental stress-induced reductions in blood flow to the heart is much more common than has been previously recognized."

In general, studies have shown that as many as two-thirds of patients with coronary artery disease who experience exercise-related reductions in blood flow to the heart respond similarly to mental stress. These bouts often produce no symptoms of chest pain and are rarely detectable on a standard electrocardiogram. Yet last year UF researchers found that these patients have a threefold greater risk of dying - as large a risk factor as cigarette smoking or high cholesterol. Other studies have linked stress experienced after mass disasters or natural catastrophes with a rise in heart attacks and sudden death.

Psychological stress can leave the heart more prone to developing arrhythmias or electrical instability and the blood more prone to clotting. Stress appears to raise heart rate and rapidly hike blood pressure, increasing the heart's need for oxygen-rich blood, Sheps said. Yet less oxygen is supplied, in part because coronary arteries constrict, impeding blood flow. Doctors are concerned that this reaction to stress in the laboratory is simply a snapshot of how patients respond to the stress of life day in and day out.