A nationwide study of heart attack victims finds that a surprising number — one-third — did not experience chest pain.

Women, nonwhites, people older than 75 and those with previous heart failure, stroke or diabetes are most likely to have ``painless'' heart attacks, according to a study in the Journal of the American Medical Association.

These patients are more than twice as likely to die, due in part to delays in seeking treatment and because doctors might fail to diagnose them quickly.

Patients with chest pain were more than twice as likely to be diagnosed upon admission and to get either clot-busting drugs or angioplasty, in which a balloon-tipped catheter is used to open blocked arteries.

Doctors and paramedics should be alerted by these findings to the need for rapid diagnosis and treatment of patients in the high-risk groups, according to the report. Other less typical symptoms can include shortness of breath, irregular heartbeat, nervousness, nausea, fainting or overwhelming weakness.