JAMA: Murky CVD diagnosis? ECG could help

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Predicting coronary heart disease (CHD) with traditional risk factors may be imprecise, but adding ECGs to the mix may help, especially in the elderly patient population, according to study results published in the April 11 issue of the Journal of the American Medical Association.

“Resting electrocardiographic (ECG) abnormalities have been shown to be independently associated with incident CHD and cardiovascular disease (CVD) events, and ECG is a good candidate to consider for risk stratification of asymptomatic participants given its low cost, wide use, and safety,” wrote Reto Auer, MD, of the University of California, San Francisco, and colleagues.

To better understand whether the ECG can help predict CHD risk, Auer et al performed a population-based study of 2,192 patients who were age 70 to 79 years from the Health, Aging and Body Composition Study (Health ABC) who had no perceived cardiovascular disease. Data were collected over an eight-year time period between 1997-1998 and 2006-2007. The researchers used adjudicated CHD events (acute MI, CHD death and hospitalization for angina or coronary revascularization) as the study’s primary endpoint.

At the start of the study, 13 percent of patients had minor ECG abnormalities and 23 percent had major ECG abnormalities. At follow-up, 351 patients experienced a CHD event (96 CHD deaths, 101 acute MIs and 154 hospitalizations for angina or coronary revascularization). The authors noted that both minor and major ECG abnormalities were linked to an increased risk of CHD after the adjustment of traditional risk factors (17.2 per 1,000 person-years in those who had no abnormalities, 29.3 per 1,000 person-years for those with minor abnormalities and 31.6 per 1,000 person-years for those with major abnormalities).

When the researchers added ECG abnormality data to a model that contained the traditional risk factors, it was found that 13.6 percent of intermediate-risk participants with minor or major ECG abnormalities were correctly reclassified.

At four years, 208 patients had new abnormalities and 416 were found to have persistent abnormalities; both cohorts saw an increased risk of CHD events.

“What are the implications of our study,” the study authors asked. Currently, the U.S. Preventive Services Task Force (USPSTF) does not recommend ECG screening for asymptomatic populations. This is due to the fact that few clinical trials exist testing the benefits of ECG screening in younger populations.

“The ECG screening may be useful among populations of older adults, but the benefit was small and our results need to be validated in additional cohorts,” the authors wrote. “The safety, low cost, and wide availability of ECG are advantages as a screen for subclinical CVD.

“An electronic method of reading the ECGs might facilitate the use of ECG data in clinical practice by permitting direct inclusion of data into an individual risk calculator alongside other CVRFs [cardiovascular risk factors] of EHRs,” they wrote.

"Anytime someone goes into the emergency room, especially elderly people, they typically get an ECG," Auer said.

"So in the patient's electronic record system, you could include these ECG abnormalities as part of the patient's overall risk – but we're not there yet," added study co-author Douglas C. Bauer, MD, director of UCSF's Division of General Internal Medicine Research Program, in a statement.

Some societies, like USPSTF, have exuded trepidation with who receives ECGs, particularly in asymptomatic patients. And while the researchers found current study results to be promising, they said it will be important for clinical trials to be conducted to understand whether ECG should be added to routine screening in older populations.