Stress-induced blockages raise risk for death in people with heart disease

Nov. 9 (UPI) -- Stress worsens heart disease symptoms and increases the risk for death from heart attack or stroke among those with the condition, a study published Tuesday by JAMA found.

Blockages in blood flow to the heart, known as myocardial ischemia, caused by stress more than double the risk for death in people with coronary heart disease, even if their heart disease is "stable" and well-controlled by treatment, the data showed.

Participants in the study with mental stress-induced myocardial ischemia had a 2 1/2 times higher risk for death from a heart-related "event," such as a heart attack or stroke, over the next five years compared with those without the condition.

All of the participants in the study had been diagnosed with heart disease and were considered stable due to treatment, according to the researchers.

"Psychological stress is a powerful risk factor for adverse outcomes in people with heart disease," study co-author Dr. Viola Vaccarino told UPI in an email.

"Exposure to acute stress can cause a reduction of blood flow to the heart muscle in some people, and this can increase their risk of cardiac events or death," said Vaccarino, a professor of cardiovascular research at Emory University in Atlanta.

More than 18 million adults in the United States, or about 7% of the population, have coronary heart disease, making it the most common form of heart disease, the Centers for Disease Control and Prevention estimates.

It is caused by a reduction in blood flow to the heart muscle due to build-up of plaque in heart arteries.

The condition kills nearly 400,000 people per year and is the leading cause of death nationally, the CDC says. More than half of adults in the United States experience significant mental stress, the American Psychological Association estimates.

For this study, Vaccarino and her colleagues studied the effects of stress on 918 adult participants, ages 18 to 79 years, with stable coronary heart disease. About 300 of participants had been hospitalized after a heart attack during the eight months before the study began.

For the study the researchers "induced" mental stress in participants by having them perform a public speaking task.

Participants were given two minutes to prepare a speech and three minutes to deliver it in front of an audience of at least four people.

Their mental stress levels were assessed based on blood pressure and heart rate, which were recorded throughout the public speaking task, the researchers said.

In addition, the researchers measured participants' "conventional" stress, or the stress on the heart muscle caused by physical exercise, using a standard cardiac stress test, which measures heart function during physical activity.

Among the study participants, 147 patients, or 16%, developed mental stress-induced myocardial ischemia and 281, or 31%, had conventional stress-induced myocardial ischemia, with 96, or 10%, suffering both.

Twelve, or 8%, of the participants who had mental stress-induced myocardial ischemia died from a cardiovascular-related cause within five years, the researchers said.

In comparison, 4% of those who did not develop mental stress-induced myocardial ischemia died from a heart-related cause within five years.

About 12% of participants with mental stress-induced myocardial ischemia died from any cause within five years, compared with just under 8% of those without the condition, the data showed.

"This was not because these individuals were sicker, or prone to reduction in blood flow with other forms of heart challenge, like a physical stress using treadmill," Vaccarino said.

"Actually, those who developed ischemia with mental stress only were at higher risk of recurrent events and death than those who developed ischemia with a conventional stress test only," she said.