"Silent" heart attacks more common than thought

Fri Apr 17, 2009 3:21pm EDT
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By Julie Steenhuysen

CHICAGO (Reuters) - A study using new imaging technology found "silent" heart attacks may be far more common, and more deadly, than suspected, U.S. researchers said Friday.

Some studies estimate that these often painless heart attacks, also known as unrecognized myocardial infarctions, affect 200,000 people in the United States each year.

But Dr. Han Kim of Duke University in North Carolina suspects the numbers may be far higher.

"No one has fully understood how often these heart attacks occur and what they mean, in terms of prognosis," Kim, whose study will appear next week in the Public Library of Science journal PLoS Medicine, said in a statement.

Doctors usually can tell whether a patient has had a recent heart attack by looking for signature changes on a test of the heart's electrical activity called an electrocardiogram and by checking for certain enzymes in the blood.

For a heart attack that might have occurred in the past, doctors look for changes on an electrocardiogram called a Q-wave, a marker for damaged tissue.

But not all silent heart attacks result in Q-waves.

"Those are the ones we haven't been able to count because we've never had a good way to document them," Kim said.   Continued...