ECGs measure electrical activity in the heart
Heart tests offered to many patients with chest pain are of little value in predicting future heart disease, say researchers.
Instead of electrocardiagram (ECG) tests, doctors should spend more time quizzing patients about their symptoms and examining them, they said.
The British Medical Journal study, by the London Chest Hospital, followed 8,176 suspected angina patients.
A heart charity stressed that the test was useful in other circumstances.
Approximately two in 100 people in the UK experience angina, which is the most common symptoms of heart disease.
Reporting chest pain to a doctor generally means referral to a rapid access clinic, where ECGs taken to predict whether a patient needs further attention.
An ECG monitors the electrical activity of the heart over a period of time, looking for evidence of weakness in the heart muscle, or abnormal rhythms.
Often the patient will be asked to undergo the test while exercising, which can help highlight these problems.
The study compared the progress of the patients, 60% of whom who had an exercise ECG performed.
Among the 60%, 1,422 not only had the basic "summary" results recorded, but had detailed data from the ECG used to help make a diagnosis.
All the patients were then followed up for the next few years.
However, almost half of all coronary "events", such as heart attacks, that happened during this period, happened in patients whose ECG results had not shown any sign of problems.
A routine clinical assessment, which involved taking a detailed "history" from the patient, and examining them thoroughly, was almost as good in predicting future heart disease as the exercise ECG.
The researchers concluded that the tests were "of limited value" to doctors faced by patients with no prior heart disease.
Dr Mike Knapton, from the British Heart Foundation said that while early diagnosis of angina was important, the study showed that the best way to achieve that was to talk to the patient.
"Tests such as resting or exercise ECGs can be helpful when patients present with unusual symptoms or suffer from chest pain following a heart bypass.
"But exercise ECG is not very good at assessing future risk. Better risk assessment of patients with angina is needed to help identify those most at risk of heart attack or death.
"Any results for ECGs should be in addition to consultation with your Doctor to properly monitor your condition."