Silent but deadly: almost half of heart attacks cause no initial symptoms - but they’re still dangerous

Almost half of all heart attacks cause no obvious symptoms, yet they can still be life-threatening, according to research on more than 9,000 middle-aged men and women.

It’s one of the biggest studies to examine so-called silent heart attacks, and to also explore them across racial and gender groups.

Researchers at Wake Forest University’s medical school led the government-funded study. Results were published online Monday in the American Heart Association’s journal, Circulation.

Middle-aged adults from four US communities were enrolled: Washington County, Maryland; suburban Minneapolis; Jackson, Mississippi and Forsyth County, North Carolina. The study’s aim was to examine causes of age-related artery damage that can lead to heart disease. Whites and blacks were included.

Participants had periodic clinic exams including electrocardiograms and phone interviews with the researchers. They were followed for about 13 years.

Overall, 45 per cent of heart attacks were the silent kind, which are usually discovered some point later when a patient has an abnormal EKG reading that suggests previous heart damage.

Silent heart attacks were found on EKGs in 317 participants, or about 3 per cent, who hadn’t had suspicious symptoms. By contrast, 386 patients, or 4 per cent, had had full-blown heart attacks with symptoms. Symptoms often include chest pain, jaw and arm pain and shortness of breath. Silent heart attacks may cause mild fatigue or other vague symptoms that don’t seem serious.