UF Cardiologists Garner Federal Funds To Study Stress And The Heart

February 25, 2004

GAINESVILLE, Fla. — You may have sworn off the burger brigade, and started eating healthy and watching your weight, with a dose of frequent exercise for good measure. But take this to heart: If you have coronary artery disease, stress could be just as dangerous as high-fat foods or smoking.

University of Florida cardiologists are using more than $4.5 million in new federal grant money to fund two studies of the short- and long-term effects of stress on blood flow to the heart.

In one project, they will evaluate whether a certain cardiac imaging technique can be used to reliably identify high-risk patients with heart disease who experience mental stress-induced reductions in blood flow to the heart but who don’t suffer outward symptoms such as chest pain. The scientists also will study whether abnormal responses to mental stress increase the risk of death and other cardiovascular complications in these patients.

In a second, first-of-its-kind study of patients with heart disease, UF researchers will evaluate whether meditation and yoga are better at reducing stress and improving heart health than simply educating patients about heart disease or asking them to record stressful events in a daily diary.

“The reason we’re interested in it is there are now at least four published studies that indicate that patients who have (reductions in blood flow to the heart) associated with psychological stress have worse outcomes than those who don’t,” said Dr. David S. Sheps, associate chief of cardiovascular medicine at UF’s College of Medicine and Gainesville’s Malcom Randall Veterans Affairs Medical Center. “Patients who develop this response to stress may be having repeated bouts of this during normal daily activities, and over time that leads to worsened atherosclerosis and the increased likelihood of plaque rupture, leading to acute events (such as heart attack).”

Sheps also will discuss the projects next month at the annual meeting of the American College of Cardiology in New Orleans.

Both acute and chronic mental stress and other psychological factors such as anxiety, depression or anger are known risk factors for heart attack, hospitalization for chest pain, or the need for bypass surgery or angioplasty. In a previous study, Sheps found that mental stress can markedly decrease blood flow to the heart, hiking the risk of dying threefold – 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.

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. Studies have shown that as many as two-thirds of patients with coronary artery disease experience stress-related reductions in blood flow to the heart during daily activities. These bouts of reduced blood flow often produce no symptoms of chest pain and are rarely detectable on a standard electrocardiogram.

“It’s a bad combination,” Sheps said. “On the one hand, you have a situation with decreased blood flow and at the same time the heart requires more blood. It’s also been shown that during psychological stress the heart is more prone to developing arrhythmias or electrical instability, blood is more prone to clotting and there is an elevation in cytokines, which have been shown to be related to progression of atherosclerosis.”

In the first study, UF researchers will evaluate 300 patients with heart disease between the ages of 30 and 80 who do not exhibit symptoms such as chest pain during stress yet experience reductions in blood flow to the heart. Study participants will be asked to join a role-playing exercise involving a simulated confrontation.

The scientists will use a nuclear medicine imaging technique to assess blood flow to the heart shortly after the task. Other images will be obtained when study participants are not experiencing mental stress. The researchers’ findings will be used to determine whether abnormal responses to mental stress increase the risk of death and other cardiovascular complications, compared with patients who do not experience reduced blood flow to the heart when stressed.

The premise of the study is that mental stress-induced bouts of reduced blood flow in the laboratory may just be a snapshot of a chronic response to the stress of life, Sheps said. The study results will provide the most definitive information to date regarding the value of using mental stress-related reductions in blood flow to the heart to predict adverse cardiac events, he added.

In the second study, UF researchers will enroll 150 patients with heart disease and randomly assign them to an eight-week program of weekly meditation and yoga sessions, or to heart disease education sessions or traditional care requiring patients to monitor the daily stress they experience and log it in a diary. The research is designed to determine which approach, if any, best reduces the incidence of reduced blood flow to the heart in response to stress and improves quality of life. Cardiac imaging will again be used to monitor reductions in blood flow to the heart in all study participants at various points in the study, and levels of stress hormones in the blood also will be measured periodically.

In both studies, researchers will track patients for a number of years to look at how they fare long-term.