Usefulness of Early Rule-In and Rule-Out Biomarker Protocols to Estimate Ischemia-Induced Myocardial Injury in Early Chest Pain Presenters

Abstract

Protocols to minimize the time between 2 measurements of troponin or a combination with copeptin have been developed to rapidly rule-in or rule-out myocardial injury (MI) in patients with chest pain. These fast track protocols to rule-in and rule-out MI are not sufficiently validated for early chest pain presenters. The "early presenter" model was tested in 107 stable patients after a short period of myocardial ischemia, induced by stenting of a significant coronary artery stenosis. High-sensitivity troponin T (hsTnT), high-sensitivity troponin I (hsTnI), and copeptin were measured at the start and 90, 180, and 360minutes after stent implantation. MI was defined as a troponin level more than the upper limit of normal (ULN) and an absolute increase of >50% ULN on the 360-minute sample. A single combined measurement of troponin and copeptin 90minutes after the onset of ischemia has a low diagnostic value. This increases when serial measurements with 90-minute intervals are included. For ruling in MI, the highest positive predictive value (with a 95% confidence interval [CI]) can be obtained when focusing only on the increase in troponin level, with a positive predictive value of 86% (70, 93) and 80% (67, 90) for hsTnT and hsTnI, respectively. For ruling out MI, a combined absence of any troponin more than the ULN and any significant increase in troponin level perform best with a negative predictive value of 75% (55, 89) and 75% (55, 89) for hsTnT and hsTnI, respectively. In conclusion, in early presenters, rapid biomarker protocols underestimate MI. A standard biomarker assessment after 3hours is required to adequately rule-in or rule-out myonecrosis.