Chicago Just because a person doesn't have chest pain doesn't mean he or she isn't having a heart attack.
Debunking a medical myth, a nationwide study of 434,877 heart attack victims found that a surprising one-third showed up at the hospital without chest pain.
Such patients were more than twice as likely to die, in part because they delayed going to the hospital and because doctors failed to diagnose them quickly, according to the study in today's Journal of the American Medical Assn.
Women, nonwhites, people older than 75 and those with previous heart failure, stroke or diabetes were most likely to have "painless" heart attacks, as previous research has shown.
Doctors have long known about painless heart attacks. But the researchers and experts not involved in the study said the magnitude of the problem is greater than they thought.
"Thirty-three percent is a huge bunch," said Dr. Lynn Smaha, president of the American Heart Assn. "I didn't know it was that large."
The researchers, led by Dr. John Canto of the University of Alabama at Birmingham, said the findings should alert doctors and paramedics to the need for rapid diagnosis and treatment of patients in the high-risk groups.
Other less typical symptoms can include shortness of breath, irregular heartbeat, nervousness, nausea, fainting or overwhelming weakness.
Heart attacks strike an estimated 1.1 million Americans each year, killing more than 40 percent of them.
The researchers analyzed 1994-98 data from a national registry of heart attack patients at 1,674 hospitals nationwide.