A genetic variation coupled with mental stress works to lower blood flow to the heart, researchers at University of Florida have found.
According to the researchers, those with the gene variation are three times more likely to experience dangerous decreases in blood flow to the heart - a condition doctors call ischemia - than heart disease patients without it.
"Searching for the presence of this gene may be one way to better identify patients who are at an increased risk for the phenomenon," 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.
Ischemia increases the chance these patients will suffer a heart attack, heart rhythm abnormalities or sudden death, said UF researchers.
"There's no question that in certain populations it is associated with worse prognosis than in patients who do not have mental stress-induced ischemia in terms of overall adverse events and also mortality," Sheps said.
"And it has become apparent that it is far more prevalent than we initially thought. Most of the studies that have been published to date have involved populations of patients who had coronary disease and positive exercise stress tests. But recently we and other investigators have shown that a much broader category of patients also are prone to mental stress ischemia," he added.
In the study, the researchers studied 148 patients with coronary artery disease who were on average about 65 years old. Participants were asked to perform a public speaking test designed to induce stress. Images were taken of blood flow to the heart at rest and during the speech task. Blood samples also were collected and analyzed for five common gene variations.
About a fourth of the patients experienced mental stress-induced reduced blood flow to the heart, and about two-thirds of them harbored a particular variation of the adrenergic beta-1 receptor genotype that was associated with a three-fold increased risk of this phenomenon, said Mustafa Hassan, M.D., the study's lead author and a research fellow in UF's division of cardiovascular medicine.
This receptor typically helps the body respond to stress by regulating blood pressure and heart rate, but a common variability in its gene may make certain patients more vulnerable to the effects of psychological stress.
The study is published in the Archives of Internal Medicine.