"In patients with stable chest pain, suspected angina, the resting EKG was of no incremental prognostic value as a means of assessing the risk of patients having further coronary events," said study author Dr. Adam Timmis, a professor of clinical cardiology at London Chest Hospital. The findings were published in the Nov. 14 online issue of the BMJ.
Chest pain is the most common reason people seek medical attention for possible heart trouble, and an EKG, also known as an ECG, is a common test for such people, Timmis said. "We were interested in the value of the EKG as a stand-alone predictor, its incremental value in addition to taking a history, doing a physical examination and so on," he said.
Timmis and his colleagues followed 8,176 patients with no history of heart disease who were referred to chest pain clinics because of suspected angina. All had EKGs done while they were resting, and 60 percent of them also had EKGs while they exercised. All had the usual clinical assessment, recording data such as age, sex, duration of symptoms, smoking status, high blood pressure history and medications they were taking.
The patients who had exercise EKGs done were split into two groups: "summary" results were recorded for 4,848, while additional "detailed" results were recorded for 1,422. All were then followed for several years. The researchers found that 47 percent of the coronary events that occurred happened to people whose exercise EKGs did not indicate any heart problems.
"We found that the exercise EKG had no added value over and above the clinical assessment," Timmis said.
The EKG does have some role in diagnosis, helping to determine whether the chest pain is caused by a heart problem, Timmis noted.
"The study is a reminder of the importance of taking a detailed history and making a thorough physical examination, and that additional information from the EKG is helpful in some patients but does not predict risk in everyone," Dr. Beth Abramson, director of the Cardiac Prevention Centre at St. Michael's Hospital in Toronto, wrote in an accompanying journal editorial.
The study showed that the combination of an EKG and a stress test can be helpful because "an abnormal EKG and abnormal stress test independently predicted adverse events, such as death or acute coronary syndrome in the cohort study," Abramson wrote.
But some people with normal EKGs and normal stress tests in the study did have coronary events, "so the study cannot provide an answer about which approach should be used in patients with a normal EKG," she wrote. "These patients need to have their cardiac risk factors assessed regularly by their general practitioner and, if necessary, modified."
The study also showed that "the stress test and EKG are not foolproof indicators of risk," Abramson wrote. "However, even though these tests cannot predict all future events, they are a necessary extension of the physical examination in patients with suspected angina."
Timmis said, "We are looking for better tests to classify patients in terms of risk." Some newer methods show promise, "but all these tests need to be assessed not for their standalone value but for clinical value in these patients."
More information
More details on EKGs are described by the U.S. Library of Medicine.
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