Doubts over ECG tests

Monday November 17th, 2008

ECG tests for the heart may not add a great deal to the assessment of people with suspected angina, researchers have claimed.

Basic clinical assessment is nearly as good at predicting the likelihood of future heart disease, write Professor Adam Timmis and colleagues from Barts and The London NHS Trust, UK, on the website of the British Medical Journal.

They investigated the utility of resting and exercise ECGs - which use electrodes to measure heart rate. A total of 8,176 participants were recruited from six chest pain clinics in England with suspected angina and no previous diagnosis of heart disease.

All were clinically assessed and given resting ECGs. Sixty per cent also had an exercise ECG. Over the next six years, almost half (47 per cent) of the coronary events that occurred, took place among patients whose exercise ECGs were clear.

The authors believe that exercise ECGs are "limited in how accurately they predict the risk of future heart disease".

They conclude: "In ambulatory [able to walk] patients with suspected angina, basic clinical assessment encompasses nearly all the prognostic value of resting ECGs and most of the prognostic value of exercise ECGs.

"The limited incremental value of these widely applied tests emphasises the need for more effective methods of risk stratification in this group of patients."

In an accompanying editorial, Dr Beth Abramson of St Michael's Hospital in Toronto, Canada, points out that "additional information from the ECG is helpful in some patients but does not predict risk in everyone".

"The results do not mean that ECGs and stress tests are not useful," she adds, because abnormal results "independently predicted adverse events, such as death or acute coronary syndrome in the cohort studied".

Sekhri, N. et al. Incremental prognostic value of the exercise electrocardiogram in the initial assessment of patients with suspected angina. The British Medical Journal, 2008;337:a2240.

Abramson, B. Prognostic value of electrocardiography in suspected angina. The British Medical Journal, 2008;337:a2340.

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