More than four in 10 heart attacks go undiagnosed at the time they occur, a new European study reports. And these so-called "silent heart attacks" occur more often in women than in men.

The Study

For the study, researchers analyzed more than 4,000 men and women older than 55 who were participating in the Rotterdam Study. A baseline electrocardiographic screening (ECG) and medical examination showed no evidence that any of the participants had had a heart attack. The subjects then underwent at least one follow-up examination several years later.

n total, 43% of the heart attacks went unrecognized by the patients themselves and by doctors, including one-third in men and more than one-half in women, the researchers found.

The results for women are particularly troubling. "Clearly heart attacks are being missed in women, and these are women who were in the health-care system," says Dr. Nieca Goldberg, former chief of women's cardiac care at Lenox Hill Hospital in New York City, and author of The Women's Healthy Heart Program.

Previous studies that have been conducted have indicated that up to 44% of ischemic heart attacks are clinically unrecognized, but the data have been limited and contradictory.

Although the study was conducted in the Netherlands, the researchers believe the results would apply to any other developed country.


"There is quite a proportion of myocardial infarctions [heart attacks] that is clinically unrecognized by the patient him- or herself, and also by the medical system," says study coauthor Eric Boersma, an associate professor of clinical cardiovascular epidemiology at Erasmus Medical Centre in Rotterdam, the Netherlands.

Atypical symptoms, different symptoms in women and men, as well as in the elderly and diabetics, may explain why heart attacks often go unnoticed. However, it's important to identify people who have had silent heart attacks because they are at a higher risk of experiencing additional cardiovascular complications.

"We know from other research that unattended myocardial infarctions do have prognostic implications in the sense of lower life expectancy," Boersma says.

The study authors suggest that periodic, repeat ECGs be performed to find out if there is any evidence of silent heart attacks that had previously gone unnoticed, and patients could then be treated accordingly, with aspirin, beta-blockers, statins and lifestyle changes.

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