London, Nov 14 : Scientists have claimed that ECG (electrocardiogram) tests, which are commonly given to people with suspected angina to predict the likelihood future of heart disease, have limited accuracy.
Angina is the most common symptom of coronary artery disease. Patients are assessed at rapid access chest pain clinics, designed to ensure that a specialist can assess people who develop new symptoms of suspected angina within two weeks of referral.
A study published on the online British Medical Journal has claimed that despite of conducting ECG, there is still need for alternative tests, which add predictive value to that obtained from the patient's clinical history.
The authors said that this could improve the chances of detecting people at higher risk of future heart disease and heart attacks.
The most commonly performed non-invasive test used in suspected angina patients is the immediate assessment using ECG while patients are resting and when they are exercising, but its ability to predict future heart disease is unknown.
Led by the London Chest Hospital, the researchers studied 8176 patients with suspected angina and no prior diagnosis of heart disease, who were referred by their doctor to one of six chest pain clinics.
All the patients were clinically assessed (studying data such as age, sex, ethnicity, duration of symptoms, description of chest pain, smoking status, history of hypertension, medications) as well as having an ECG done while they were resting.
4873 of the patients had an exercise ECG performed and were split into two groups, one comprising 4848 patients with a "summary" result recorded, and the other with 1422 patients who additionally had "detailed" exercise ECG data recorded. All patients were followed up for the next few years.
It was found that close to fifty percent of all coronary 'events' that happened to people during the follow up period occurred in patients who had had a negative exercise ECG that did not indicate any heart problems.
The authors said that the results indicate that exercise ECGs are limited in how accurately they predict the risk of future heart disease.
They found that a routine clinical assessment provided almost as much predictive information about future heart problems as having an ECG.
The resting ECG showed no additional benefit to the information obtained from the history and examination.
The authors concluded that ECG tests are of limited value in identifying potential future coronary problems in patients with suspected angina and no prior diagnosis of heart disease, adding little to routine clinical assessment including the patient's history and an examination.
The researchers said: "The limited incremental value of these widely applied tests emphasises the need for more effective methods of risk stratification in this group of patients."