pressure, or who have diabetes," Walters said on the opening day of the four-day American Heart Association (AHA) national scientific meeting here.
"There's a lot we can do for them, but we need to know to do it."
Other researchers at the meeting reported that:
* Fish oil fed to rhesus monkeys blocks hardening of the arteries induced by high-fat foods.
* The herpes virus that causes cold sores may also be one of the causes of a deadly heart disease known as atherosclerosis.
* Heart-attack patients who participate in exercise rehabilitation programs have a rate of long-term survival 35 percent above that of nonparticipants.
* Depression was a significant predictor of which patients would die within three months of having a heart attack.
In the South Carolina study on silent heart disease, Walters and his colleagues used stress tests to identify 55 patients with myocardial ischemia, a disease caused by insufficient blood flow to the heart's muscle.
Twenty-eight of the ischemic patients had no symptoms of a heart problem, while the other 27 suffered from sharp chest pains known as angina.
An average of 30 months later, six of the symptomless patients had had heart attacks, three of them fatal. Only one angina sufferer had an attack, and it was not fatal.
Walters said the findings were significant, expecially considering that past studies have indicated that 80 percent of ischemic episodes are painful.
"There's a lot of ischemia that's not being treated," he said.
Silent ischemia can be treated with drugs and sometimes surgery, Walters said, but only if people with the disease are detected.
"We can't screen all of America; that would be too expensive," Walters said. "Besides, even though some people are very interested in knowing if they have a disease, some people don't know and don't want to know."
In the fish-oil study, University of Chicago scientists demonstrated for the first time that fish oil directly reduces cholesterol buildup in primates. The results add to a growing body of evidence suggesting that a diet rich in fish can help prevent heart disease.
"It looks great," said Harry Davis of the Chicago team. "We were very, very excited by this."
But Davis cautioned against taking pure fish oil as a preventive measure.
"Right now, I would recommend eating more fish," he said, "but I wouldn't go so far as saying you should go and buy those fish oil supplements that are available.
"I'd say if you followed AHA's general diet, lowering total cholesterol and fatty foods, and eat more fish, you'll be doing all right."
Regarding the possible connection between the herpes virus and atherosclerosis, Dr. David Hajjar, associate professor of biochemistry and pathology at Cornell University Medical Center in New York City, said the herpes simplex virus type 1, for which there is no cure, inhibits the body's mechanism that normally would break down fatty particles in the arteries.
This leads to an accumulation of the particles, of which cholesterol is the most common, and the narrowing of the arteries, resulting in atherosclerosis, which is responsible for 700,000 deaths a year in the United States.
"Our theory is that if you have many herpes viral infections during your lifetime, and the virus localizes in the arteries, cholesterol accumulates in your arteries each time you are infected. . . . This accumulation increases your risk of heart and blood vessel disease," Hajjar said.
The AHA meeting was expected to attract more than 17,000 doctors, scientists, nurses and others.
"It is clearly the most important meeting in the cardiovascular field in the world," program chairman Dr. August Watanabe said of the 59th annual scientific sessions of the American Heart Association. Watanabe chairs the department of medicine at Indiana University.
Researchers will present 2,057 papers on heart and blood vessel disease. Watanabe said primary interests would be studies of cholesterol, treatment for heart-attack patients and the molecular biology of heart disease. The sessions also will include one on the economics of heart disease.