Nearly 200,000 people in the US have a heart attack each year, and may never even know it. So-called "silent" heart attacks don't cause any pain or major discomfort, and aren't always detected on standard electro-cardiogram, or ECG tests.
Duke University researchers used a different type of imaging, to try to find evidence of silent heart attacks in 185 patients suspected of having coronary artery disease. None had been diagnosed with heart attacks.
Researchers say they found signs of a previous, undetected heart attack in 35-percent of the patients. Those silent heart attacks were also found to increase the risk for premature death significantly.
More research is needed for doctors to understand how to treat patients with these silent heart attacks.