Thursday, May 14, 2009

Is Silent Heart Attack Common?

The American Heart Association had declared heart disease as the number one killer in the United States. In general, people with high blood pressure, diabetes, high cholesterol, as well as those who are overweight or obese are at a high risk of getting heart disease.

According to a new study, the so-called silent heart attacks may be far more common than previously thought. Each year, there are nearly 200,000 Americans suffering such an attack without even realizing it.

In a paper published on April 20, 2009 in PLoS Medicine, a peer-reviewed publication of the Public Library of Science, the researchers from Duke University Medical Center reported that the unrecognized myocardial infarction (UMI) could be difficult to detect, if it occurred in the distant past, and it often goes unnoticed by the victim. It is, nevertheless, associated with a high risk of sudden death. They also pointed out that no one has yet fully understood how often these heart attacks occur and what they mean, in terms of prognosis.

The new study had led to the belief that the subset of heart attacks, known as non-Q-wave UMIs, is fairly common, at least among people with suspected coronary artery disease.

Doctors usually depend on specific alterations of an electrocardiogram (EKG) called a Q-wave that signals damage of heart tissue so that they could detect heart attacks, which happened in the distant past. However, many UMIs do not result in Q-waves on an EKG, leading to a previously unknown number of silent heart attacks.

In the study, the Duke researchers used a technique known as delayed enhancement cardiovascular magnetic resonance (DE-CMR) to examine 185 patients, who were suspected of having coronary artery disease but who had no record of any heart attacks.

These patients were studied for 2 years and it was found that 35 percent of them had evidence of a heart attack, and that non-Q-wave UMIs were 3 times more likely than Q-wave attacks. Furthermore, those who suffered non-Q-wave attacks had 17 times higher chance of dying of heart attacks than those with no heart damage.

The researchers also suggested that if patients with UMIs happen to be identified, they could have been treated in a similar manner as those patients who were known to have heart disease.

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