ECG abnormalities associated with increased risk of CHD in older adults

In a study that included elderly men and women without preexisting cardiovascular disease, major and minor electrocardiographic abnormalities were associated with an increased risk of coronary heart disease (CHD) events and improved the prediction of CHD events such as heart attack, beyond traditional cardiovascular risk factors, according to a study in the April 11 issue of JAMA.

"In populations of older adults, prediction of CHD through traditional risk factors is less accurate than among middle-aged adults," according to background information in the article. Electrocardiographic (ECG) abnormalities are common in older adults. "However, performing routine ECG among asymptomatic adults is not supported by current evidence. Considering the higher prevalence of both cardiovascular disease (CVD) and ECG abnormalities in older adults, risk prediction incorporating ECG might be more useful in this group. To date, few studies have examined the improvement of CVD risk prediction using ECG abnormalities in a population of older adults and none could adequately adjust the analyses for presence of previous CVD and traditional cardiovascular risk factors (CVRFs)."

Reto Auer, M.D., of the University of Lausanne, Switzerland, and University of California, San Francisco, and colleagues conducted a study to determine whether baseline (at the beginning of the study) major and minor ECG abnormalities, development of new ECG abnormalities, and persistent ECG abnormalities during follow-up were associated with new CHD events, independent of traditional cardiovascular risk factors. The population-based study included 2,192 white and black older adults ages 70 to 79 years without known cardiovascular disease. Adjudicated CHD events were collected over 8 years between 1997-1998 and 2006-2007. Baseline and 4-year ECG abnormalities were classified as either major and minor. The addition of ECG abnormalities to traditional risk factors were examined to predict CHD events.

Of the 2,192 participants in the study, 506 (23 percent) had major and 276 (13 percent) had minor ECG abnormalities. During a median (midpoint) follow-up of 8.2 years, 351 participants had CHD events (96 CHD deaths, 101 acute myocardial infarctions (MIs; heart attack), and 154 hospitalizations for angina or coronary revascularizations) and 602 died (96 deaths from CHD). Analysis of data indicated that major and minor ECG abnormalities at baseline were both associated with an increased risk of CHD. After adjustment for various cardiovascular risk factors, including age, sex, total and high-density lipoprotein cholesterol, systolic blood pressure, smoking, and diabetes, compared to participants without ECG abnormalities, participants with minor ECG abnormalities at baseline had a 35 percent increased risk for CHD events, and participants with major ECG abnormalities had a 51 percent increased risk. Stratification of analyses by race showed similar findings between white and black participants.

"The addition of ECG abnormalities to the model adjusted for traditional CVRFs resulted in reclassification of 13.6 percent of intermediate-risk participants and 7.1 percent in the overall sample. When ECG abnormality was added to the model adjusted for traditional CVRFs, 176 intermediate-risk participants (8 percent) were reclassified as high risk, of whom 27 (15.2 percent) experienced events. Conversely, 136 participants (6.2 percent) were reclassified as low risk, of whom 7 (5.2 percent) experienced events," the authors write. Including ECG abnormality in the model adjusted for CVRFs placed 65 percent of the overall population into either the highest-risk or lowest-risk categories vs. 49 percent with traditional risk factors alone.

After 4 years, 208 participants had new and 416 had persistent abnormalities. After adjustment for CVRFs, both new and persistent ECG abnormalities at 4 years were associated with an increased risk of subsequent CHD events.

"In conclusion, we found that major and minor ECG abnormalities are associated with future CHD events and provide modestly improved risk reclassification beyond traditional risk factors. Risk prediction with traditional risk factors is less accurate in older persons compared with middle-aged adults. Given the safety, the low cost, and the wide availability of ECG, ECG data might be useful to improve CHD risk prediction in older adults. Whether ECG should be incorporated in routine screening of older adults should be evaluated in randomized controlled trials," the researchers write.

In an accompanying editorial, Philip Greenland, M.D., of the Northwestern University Feinberg School of Medicine, Chicago, writes that regarding the question if there should be routine screening with resting ECG in asymptomatic patients, several groups currently advise against this practice.

"These include the U.S. Preventive Services Task Force and the American College of Cardiology Foundation/American Heart Association (although some specific higher-risk groups were considered as possible targets of such testing). Even Consumer Reports has recommended against routine ECG testing. For the time being, in the absence of clear evidence of benefit and no clear implications for costs, the best advice is not to perform ECGs in asymptomatic patients, regardless of age. However, a careful and detailed cost-effectiveness analysis would be a useful next step in the translation of the cumulative risk information into an evidence-based practice recommendation."