Improved identification of acute coronary syndromes with delta cardiac serum marker measurements during the emergency department evaluation of chest pain patients.

Current findings from the American College of Emergency Physicians (ACEP) are that no serum marker reliably identifies or excludes acute myocardial infarction (AMI) within 6 h of symptom onset. The ACEP recommends repeat serum marker testing 6-10 h after symptom onset for CK-MB mass and subform, and 8-12 h after symptom onset for cardiac troponin I and T before making an exclusionary diagnosis of non-AMI chest pain. A new approach for identifying myocardial necrosis is to rely on time changes in the serum marker value over an abbreviated time interval (slope or delta values) as opposed to the traditional approach of relying on a value exceeding the threshold of normalcy. As assays become ever more sensitive and precise, this approach has the potential for both reliably identifying and excluding AMI (and subsets of high-risk unstable angina) at earlier time intervals with no loss in specificity. This article discusses some of the experimental evidence for this delta approach and some preliminary evidence for the potential of utilizing second-generation cTnI assays for the identification of acute coronary syndromes. Finally, we discuss a unique way of viewing receiver-operating characteristic (ROC) curves as catalogs of likelihood ratios, which we believe will be more useful to the clinician in the proper interpretation of serum marker values.