Association of Major and Minor ECG Abnormalities With Coronary Heart Disease Events
What is the association between baseline electrocardiogram (ECG) abnormalities or development of new and persistent ECG abnormalities with increased coronary heart disease (CHD) events?
This was a population-based study of 2,192 white and black older adults ages 70-79 years from the Health, Aging, and Body Composition Study (Health ABC Study) 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 according to the Minnesota Code as major and minor. Using Cox proportional hazards regression models, the addition of ECG abnormalities to traditional risk factors was examined to predict CHD events. The main outcome measures were the adjudicated CHD events (acute myocardial infarction [MI], CHD death, and hospitalization for angina or coronary revascularization).
At baseline, 276 participants (13%) had minor and 506 (23%) had major ECG abnormalities. During follow-up, 351 participants had CHD events (96 CHD deaths, 101 acute MIs, and 154 hospitalizations for angina or coronary revascularizations). Both baseline minor and major ECG abnormalities were associated with an increased risk of CHD after adjustment for traditional risk factors (17.2 per 1,000 person-years among those with no abnormalities; 29.3 per 1,000 person-years; hazard ratio [HR], 1.35; 95% confidence interval [CI], 1.02-1.81; for minor abnormalities; and 31.6 per 1,000 person-years; HR, 1.51; 95% CI, 1.20-1.90; for major abnormalities). When ECG abnormalities were added to a model containing traditional risk factors alone, 13.6% of intermediate-risk participants with both major and minor ECG abnormalities were correctly reclassified (overall net reclassification improvement [NRI], 7.4%; 95% CI, 3.1%-19.0%; integrated discrimination improvement, 0.99%; 95% CI, 0.32%-2.15%). After 4 years, 208 participants had new and 416 had persistent abnormalities. Both new and persistent ECG abnormalities were associated with an increased risk of subsequent CHD events (HR, 2.01; 95% CI, 1.33-3.02; and HR, 1.66; 95% CI, 1.18-2.34; respectively). When added to the Framingham Risk Score, the NRI was not significant (5.7%; 95% CI, −0.4% to 11.8%).
The authors concluded that major and minor ECG abnormalities among older adults were associated with an increased risk of CHD events.
This study suggests that in a population-based study of elderly men and women without pre-existing CHD, ECG abnormalities were associated with an increased risk of CHD and significantly improved the prediction of CHD events beyond traditional risk factors. Given the safety, the low cost, and the wide availability of ECGs, ECG data might be useful to improve CHD risk prediction in older adults. Given the relatively small sample size and other limitations of the current analysis including lack of good model calibration, the benefits of ECG screening should be examined in prospective clinical trials, as recommended by the US Preventive Services Task Force, prior to systematic screening in asymptomatic populations.
Keywords: Outcome Assessment (Health Care), Coronary Artery Disease, Myocardial Infarction, Follow-Up Studies, Calibration, Minnesota, European Continental Ancestry Group, Coronary Disease, Risk Factors, Electrocardiography, Incidence, Cardiovascular Diseases, Confidence Intervals, African Continental Ancestry Group, Hospitalization
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