Guidelines issued by the European Society of Cardiology (ESC) break ground in recommending a high sensitivity cardiac troponin assay as part of a validated algorithm to quickly and effectively rule in or rule out myocardial infarction (MI).
High-sensitivity troponin assays have yet to be approved for clinical use in the United States, although they are in clinical use in other parts of the world, including Europe, Canada, and Australia. An article on the society’s new set of guidelines appears in the European Heart Journal.
This is a crucial tool for making a faster diagnosis of MI, said Marco Roffi, MD FESC, FACC, of University Hospital in Geneva, Switzerland, and chairperson of the ESC task force that wrote the guidelines, in a video interview.
“The guidelines have documented and encouraged the use of a new algorithm for early diagnosis of myocardial infarction,” Roffi explained. “If you measure high sensitivity troponin at presentation and after one hour, you have very high diagnostic accuracy to rule-in for myocardial infarction and also in three quarters of the patients to rule-out for it.” In addition to allowing for quicker diagnoses, it will enable the emergency room to treat the patient faster, he indicated.
Cardiac troponin levels can spike fairly rapidly in patients with this condition—usually within 1 hour, as Roffi specified, and can stay that way for at least several days. As he and the coauthors of the guidelines explain, “advances in technology have led to a refinement in cardiac troponin assays and have improved the ability to detect and quantify cardiomyocyte injury.”
Although the guidelines specifically recommend a 0 hour/3 hour algorithm, a 0 hour/1 hour test could serve as an alternative in cases where high-sensitivity cardiac troponin assays with validated algorithms are available for use.
Describing the results of several large validation cohorts, the guidelines’ authors explain that “used in conjunction with clinical and electrocardiogram findings, the 0 h/1 h algorithm may allow the identification of candidates for early discharge and outpatient management. The positive predictive value for MI in those patients meeting the ‘rule-in’ criteria was 75—80%.”
The authors make a point of recommending high-sensitivity assays on automated platforms. Compared with “sensitive” tests that have a detection rate of 20% to 50%, “high-sensitivity” tests can detect MI at rates as high as 90%. Most point-of-care (POC) assays do not qualify as either sensitive or high-sensitivity testing methods, they emphasized. While they offer quicker turnaround times, the downside is these tests aren’t as accurate, have a lower negative predictive value, and haven’t been evaluated to the same extent as automated assays.
“As these techniques continue to improve and performance characteristics are both assay- and hospital-dependent, no recommendation regarding the site of measurement (central laboratory versus bedside) can be given,” the authors stated.
Other biomarkers such as creatine kinase myocardial band (CK-MB) and copeptin may prove useful in certain clinical situations. “CK-MB shows a more rapid decline after MI as compared with cardiac troponin and may provide added value for the timing of myocardial injury and the detection of early reinfarction,” according to the guideline authors.
Copeptin could assist in quantifying endogenous stress levels in MI and other medical conditions. “As the level of endogenous stress appears to be invariably high at the onset of MI, the added value of copeptin to conventional (less sensitive) cardiac troponin assays is substantial,” the authors noted. In instances where sensitive or high-sensitivity troponin assays aren’t accessible, copeptin would serve as a good alternative to rule out MI at the early stages. “Copeptin may have some added value even over high-sensitivity cardiac troponin in the early rule-out of MI,” they offered.