New Test Speeds Up Heart Attack Care

An innovative, low-cost diagnostic test that identifies patients at risk of myocardial infarction (MI) could enhance the treatment of patients at emergency departments worldwide.

A global study, led by researchers at the University of Edinburgh, has determined that the ARCHITECTSTAT high-sensitive cardiac troponin I assay can rule out the risk of MI in 49% of patients admitted with chest pains to hospital emergency departments. The test assesses levels of troponin, a muscular protein which is elevated in blood samples following MI. Older troponin-measuring diagnostic assays were less sensitive and often required patients to have multiple blood samples assessed, increasing waiting times. The newer, more sensitive assay only requires a single sample to be assessed and allows more accurate thresholds to be used to determine MI risk. Currently, the majority of physicians use troponin levels above the 99th percentile to identify a high risk of MI. This study, conducted by Dr Andrew Chapman and colleagues, aimed to assess whether a threshold of <5ng/mL troponin would be an effective measure of MI risk.

The study involved a meta-analysis comprising 22,457 patients over 19 cohorts. Researchers found that when the 5ng/mL limit was utilised, a predictive negative value of 99.5% could be obtained for MI events, which translated as 60 missed events out of 11,012 patients with troponin levels <5ng/mL. There were no cardiac deaths among the low-troponin group of patients after 30 days, and only 7 deaths after a year, translating as a 99.9% predictive negative value for cardiac death. For comparison, this meant 5-fold fewer MI events were missed than when using the 99th percentile threshold. These results, according to the study authors, should encourage adoption of new guidelines to improve patient care.

The ARCHITECTSTAT test costs less than £5 per patient and can produce informative results in as little as 20 minutes. The adoption of the new safety threshold, combined with the use of high-sensitive assays, could, say researchers, speed up care and reduce costs by cutting hospital admissions. 

 Dr Andrew Chapman, a British Heart Foundation Research Fellow at the University of Edinburgh and the paper’s lead author, said “We believe the findings of this worldwide study will provide national and international guidelines committees with the evidence they need to recommend the use of troponin testing to rule out heart attacks much earlier in the emergency department.

“This has major potential to improve the safety and efficiency of healthcare delivery, at a time of increasing financial pressures on our National Health Service.”

Reference:

Chapman, A. R., Lee, K. K., Mcallister, D. A., Cullen, L., Greenslade, J. H., Parsonage, W., . . . Mills, N. L. (2017). Association of High-Sensitivity Cardiac Troponin I Concentration With Cardiac Outcomes in Patients With Suspected Acute Coronary Syndrome. Jama. doi:10.1001/jama.2017.17488