Early diagnosis of acute myocardial infarctions (AMI) is key for treatment or survival. New high-sensitivity cardiac troponin (hs-cTn) assays, which detect very low concentrations of this marker for cardiac injury, show promise in enabling rapid diagnosis of AMI, but exactly how to incorporate them into emergency department treatment protocols has been unclear. New research by investigators in Switzerland, Spain, and Italy published in the Canadian Medical Association Journal shows that a strategy using hs-cTn test results substantially accelerates management of AMI and enables safe rule-out, as well as accurate rule-in.
"Introducing the high-sensitivity cardiac troponin T 1-hour algorithm into clinical practice would represent a profound change, and it is therefore important to determine if it works in a large patient group," Tobias Reichlin, MD, of the division of cardiology at the University Hospital Basel in Switzerland, explained in a prepared statement.
The researchers in the Advantageous Predictors of Acute Coronary Syndromes Evaluation Study prospectively enrolled 1,320 patients who presented to the emergency department with suspected AMI. They applied an hs-cTn algorithm in the management of these patients, incorporating baseline values as well as absolute changes within the first hour to perform early rule-in or rule-out, with the final diagnosis later adjudicated by two independent cardiologists.
The rule-out criterion was defined as a base¬line hs-cTn T level <12 ng/L and an absolute change within the first hour <3 ng/L. The rule-in criterion was either a baseline hs-cTn T value ≥52 ng/L, or an absolute change within the first hour of at least 5 ng/L. Patients fulfilling neither criterion were classified in a third, observational group.
"This rapid strategy incorporating high-sensitivity cardiac troponin T baseline values and absolute changes after the first hour substantially accelerates the management of patients with suspected acute MI by allowing safe rule-out as well as accurate rule-in of acute MI in 3 out of 4 patients," the study authors concluded.