by Brendon Nafziger
, DOTmed News Associate Editor | July 31, 2012
People without symptoms and at normal risk for heart disease should probably skip electrocardiography screenings, the U.S. Preventive Services Task Force has reaffirmed.
In an update to broadly similar 2004 recommendations, the group said that evidence gained from ECGs in low-risk adults would be unlikely to add much to conventional risk analysis, which takes into account blood cholesterol levels, blood pressure and whether the person smokes.
The USPSTF decision, published Tuesday in the Annals of Internal Medicine, applies to both resting and exercise ECGs. The panel said it didn't have enough evidence to determine if asymptomatic people at intermediate or high risk from the disease would benefit from ECG screenings.
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Low risk means someone has less than a 10 percent 10-year risk of developing coronary heart disease.
For the update, the 16-member panel conducted a literature review. After doing a search, the group said it found no randomized, controlled or prospective trials looking at whether screening ECGs improve clinical outcomes in symptom-free adults.
While the group did find studies showing that abnormalities on resting and exercise ECGs correlate with a greater risk for heart attacks and other cardiovascular problems, it found little evidence that they change the "risk classification" of people and thus result in different interventions that would end up saving lives.
"Despite strong evidence that such abnormalities are associated with increased risk beyond that accounted for by assessment of traditional risk factors, understanding the usefulness of screening requires additional information on the reclassification that would result, and on whether such reclassification would lead to clinical actions that improve patient outcomes," the USPSTF said.
And while the ECG itself is not terribly risky, the group also worried about downstream harms as a result of getting an abnormal result on the tests. Between roughly one in 200 and one in 58 people who have had an ECG go on to have an angiography, which carries nearly a 1 percent chance of a serious adverse event. Also, around half a percent undergo revascularization, although there's little evidence it helps asymptomatic people, the USPSTF said.
Plus, imaging scans that follow abnormal results expose patients to ionizing radiation. Coronary angiography delivers an average effective dose of 7 millisieverts and myocardial perfusion imaging 15.6 mSv, the group said.
The USPSTF recommendations are more discouraging for ECG screenings than ones put out by heart societies. In their most recent guidelines, the American College of Cardiology and the American Heart Association said resting ECG screenings are "reasonable" for adults with high blood pressure or diabetes and "may be considered" for other asymptomatic adults. Exercise ECG could be considered for intermediate-risk adults, including sedentary people starting an exercise program, the groups said in their 2010 recommendations.