NEW ORLEANS -- Speaking in public may be more than just terrifying. The stress may be deadly.
A study released Tuesday found that people whose hearts show ominous signs of poor circulation during such mental challenges face triple the usual risk of death in the years to come.
Often people with bad hearts suffer chest pain during exertion. Their clogged arteries cannot supply enough blood to their heart muscle. But over the past decade, it has become clear that mental exertion can also overwork the heart, although often without pain. Doctors call this condition silent ischemia.
While doctors assume that silent ischemia is not a good thing, no studies until now have been large enough to prove that mental stress can actually be fatal for people with coronary artery disease.
The latest study demonstrates just how dangerous this can be for the heart. It found the annual death rate is about 4 percent among people whose hearts have bad circulation during mental stress. This is more than triple the risk faced by heart disease patients who do not react this way to mental stress.
In the study, the researchers found that public speaking is a particularly potent trigger of this heart problem. However, they said that probably anything that causes mental stress is risky for these people.
The study, conducted by Dr. David S. Sheps of East Tennessee State University, was presented in New Orleans at a meeting of the American College of Cardiology.
"As doctors, we all have had patients for whom we have no doubt that an acutely stressful situation has precipitated a cardiac event," Sheps said.
To help understand how this happens, the researchers gave three days of tests to 173 men and women with heart disease. They were asked to imagine that a relative had been mistreated in a nursing home. Then they were given two minutes to prepare a speech about the problem and five minutes to deliver it before an audience.
People's blood pressure typically soared about 40 points. Radionucleotide scanners watched their hearts. In half the volunteers, sections of the muscle of the left ventricle began to beat erratically.
Eleven of them died during three to four years of follow-up. Forty-four percent of these victims had shown the erratic heartbeats during public speaking, while 18 percent did not.
Sheps said those whose hearts reacted badly on the test seemed no more nervous or tongue-tied than those who weathered the stress without problems.
"Most people do not have sudden death during public speaking," noted Dr. Bernard Gersh of the Mayo Clinic. Instead, the study identified people with a heightened response to stresses that may lead to a heart attack.
Earlier studies have shown that such hardships as depression, the death of a spouse, losing a job or living through an earthquake increase the risk of fatal heart attacks.
However, those studies did not test victims ahead of time for silent ischemia during mental stress.
The study was financed by the National Heart, Lung and Blood Institute.