Can a simple diagnostic test used to measure a heart's electrical activity help predict heart attacks? And can that knowledge help doctors reroute their patients away from coronary heart disease?

These are the questions researchers at the University of California, San Francisco, asked in a comprehensive eight-year study focused on senior citizens in the U.S. Researchers found a higher risk of heart attack when abnormalities showed up on electrocardiogram (EKG) results of healthy elderly people.

"We did not include them if they reported a previous heart attack," says lead author Dr. Reto Auer, a research fellow at UCSF's Department of Epidemiology and Biostatistics. "So we looked at people who lived independently—not in assisted living facilities—with no history of heart attacks or coronary heart disease."

The findings, published this month in the Journal of the American Medical Association, help answer the question of whether or not EKGs can be used to detect heart disease earlier in patients who don't have chest pain or other symptoms, researchers assert.

"This research is taking the information from an EKG and adding it to other traditional risk factors to better predict who is going to have a heart attack," says second author Dr. Douglas Bauer, director of the UCSF Division of General Internal Medicine Research Program.

For eight years, researchers studied more than 2,000 healthy adults aged 70 and older in Memphis, Tenn., and Pittsburgh. Those with EKG abnormalities had more heart attacks. The results were consistent even when researchers took into account known risk factors for heart attacks, such as smoking, high cholesterol, high blood pressure, and diabetes.

At baseline, 13 percent of participants had minor EKG abnormalities and 23 percent had major abnormalities. During the follow-up period, 351 participants—or 16 percent—had coronary heart disease events. Those events included 96 heart-related deaths, 101 heart attacks, and 154 hospitalizations for chest pain or procedures to restore blood flow to the heart. Both baseline minor and major EKG abnormalities were associated with an increased risk of heart disease after adjusting for traditional risk factors.

"There was a trend towards increased coronary heart disease risk from no abnormality to minor, and from minor up to major abnormality," Auer says. "But both minor and major EKG changes were significantly associated with an increased risk of CHD."

Researchers also were interested in whether or not gender or self-reported racial differences played a role in determining a healthy person's likelihood of a future heart attack among the participants who identified themselves as either Caucasian or African American. Researchers found no correlation between elevated risk factors and gender or race.

"It was a good surprise," Auer says. "It shows that it's really the EKG changes that predict risk."

Researchers say it's premature to advocate for the widespread use of their findings in a clinical setting, but that their initial evidence suggests there may be a role for EKG in adding to traditional risk factors, to better predict who is at risk for a heart attack.

"Anytime someone goes into the emergency room, especially elderly people, they typically get an EKG," Auer says. "So in the patient's electronic record system, you could include these EKG abnormalities as part of the patient's overall risk—but we're not there yet."

For now, though, researchers recommend patients become familiar with well-established risk factors that health care providers use to counsel individuals for their risk of future heart attacks and other heart problems.

Organizations such as the American Academy of Family Physicians recommend against ordering annual EKGs or any other cardiac screening for low-risk patients without symptoms, saying there is little evidence it improves health outcomes.

The American Heart Association, however, says EKG is reasonable for assessing the risk of coronary heart disease events of adults with hypertension or diabetes, even though the U.S. Preventive Services Task Force found that there is insufficient evidence to recommend for or against routine screening in adults at increased risk of heart disease. For adults at low risk, the AHA recommends that it may be considered, while the Task Force recommends against screening. However, prediction of heart attack by major cardiovascular risk factors isn't as reliable in elderly adults as in younger individuals.

"Our view is that novel screening interventions should be tested on clinical outcomes," Auer says. "Just because you know you might be at increased risk does not mean that you will be better off if your treatment is modified as a consequence of the test."