More than 7 million people in the United States visit hospital emergency departments each year for chest pain. Considering that myocardial infarction is one of the leading causes of death among adults in the United States, hospital emergency departments have created chest pain centers with defined protocols to ensure patients recent prompt care and diagnosis. The results of a recent study of more than 14,000 patients shed new light on the use of hs-cTnT assays to rule out MI in the emergency department.
Data suggest that a single measurement of high-sensitivity cardiac troponin T (hs-cTnT) and a clean electrocardiogram (ECG) might be enough to safely send a patient with chest pain home from the emergency department (ED) without additional testing. The findings were presented at the 2014 American College of Cardiology Annual Meeting and published simultaneously online in the Journal of the American College of Cardiology.
The study included 14,636 patients who presented to the ED at a Swedish hospital and had an hs-cTnT test. Of these, 61% had an hs-cTnT below 5 nanograms per liter (ng/L). At 30 days, only 0.44% (39) of these patients had a myocardial infarction (MI). None of the patients in this group died. A total of 15 had MIs with no ischemic ECG changes.
Nearly all of the patients with an undetectable troponin level and no signs of ischemia on an ECG (99.8%) were free from MI for 30 days after being evaluated for chest pain, according to the Swedish research team presenting the results. The negative predictive value for death during the same time period was 100%, suggesting that with this strategy, 20% to 25% of admissions to hospital for chest pain might be avoided. It could also reduce overcrowding in the ED and save time for both patient and doctor.
Chest pain is the second most common symptom reported in the ED. Since there are no established ways to quickly rule out heart attack, many patients are admitted to the hospital unnecessarily, at a large cost to the patient and to society. If MI can be ruled out more quickly and patients can be sent home without being admitted, that frees up a lot of hospital beds, frees up space in the ED, and frees up time that people are even staying in an ED if this test turns out negative when they come in for chest pain.
One cardiologist, not involved in the study, said the findings were in line with previous studies looking at the use of hs-cTnT assays to rule out MI, but expressed some concerns about how the study was conducted. He questioned how carefully MIs were ruled out and how well MIs were ascertained during follow-up, both factors that could have affected the estimated benefit. Despite this, he believes that the strategy will be validated.
Although the assay used in this particular study has not been approved for use in the United States, similar troponin T tests are already used frequently at many centers in the United States.