Troponin Test Could Rule Out Heart Attack in Chest Pain Patients
October 6th, 2016
EDINBURGH, UK – A new high sensitivity blood test could rule out a diagnosis for acute coronary syndrome in two-thirds of patients presenting to emergency departments, according to a new study.
The research on a test to identify the optimal level of troponin appeared recently in The Lancet. University of Edinburgh researchers and colleagues suggest that using the test in routine practice could double the number of patients found suitable for immediate discharge from the ED.
"Until now there were no quick ways to rule out a heart attack within the emergency department," lead author Anoop Shah, MD, said in a press release from The Lancet. "We have identified a cardiac troponin concentration (less than 5 nanograms per deciliter; <5 ng/L) below which patients are at very low risk of heart attack either during the admission or in the ensuing 30 days. These patients are therefore potentially suitable for immediate and safe discharge from the emergency department. These findings could dramatically reduce unnecessary hospital admissions and provide substantial cost savings for healthcare providers."
Background information in the article notes that international guidelines recommend that patients presenting with chest pain be admitted to hospital for testing for very high levels of troponin – above the 99th percentile – which indicates that a heart attack has occurred. In general, patients must either be hospitalized or have a lengthy stay in the ED for the testing.
While high-sensitivity cardiac troponin tests currently exist, study authors says it was unclear until now whether they could identify very low-risk patients who could be safely discharged from the ED.
The study used a test more sensitive than the standard version and which can detect far lower levels of troponin in the blood. Troponin levels were measured in more than 6,000 patients with chest pain admitted to four hospitals in Scotland and the United States, with researchers prospectively evaluating the negative predictive value of a range of troponin concentrations for heart attack or subsequent death from a heart condition after 30 days.
According to the results, a troponin threshold of less than 5 ng/L at presentation identified 61% of patients at very low risk of acute coronary syndrome – and who likely could be safely discharged – with a high negative predictive value of 99.6%. The high negative predictive value persisted despite, sex, cardiovascular risk factors, or prior cardiovascular disease. After a year, those patients had a three times lower risk of heart attack and cardiac death than those who had troponin levels 5 ng/L or higher, the study notes.
“Low plasma troponin concentrations identify two-thirds of patients at very low risk of cardiac events who could be discharged from hospital. Implementation of this approach could substantially reduce hospital admissions and have major benefits for both patients and health-care providers,” study authors conclude.
Writing in a linked comment, Louise Cullen and William Parsonage from the Royal Brisbane and Women's Hospital, Queensland, Australia, and Martin Than from Christchurch Hospital, New Zealand, call for clinical trials to develop guidelines that involve no further testing for patients with low troponin concentrations.