The search for a biomarker of cardiac ischemia.

Abstract

With ∼8 million patients arriving with nontraumatic chest pain to emergency departments in the US each year, the clinical evaluation, triage, and management of patients with possible acute coronary syndromes (ACS) presents a substantial medical and fiscal challenge (1). Although 2–5% of patients with myocardial infarction (MI) are inadvertently discharged from the emergency department and are a leading reason for malpractice claims, more than 50% of patients hospitalized for evaluation of chest pain are discharged with diagnoses other than ACS (1). Among those patients with definite ACS, early treatment may reduce the extent of myocardial injury, and thus rapid diagnosis and initiation of therapy is a central tenet of management (2). In addition, given the increasing array of treatments for the heterogeneous population of patients admitted with definite ACS, effective risk stratification and targeting of therapy have become a focus of contemporary management of ACS (2)(3). As such, the objectives of the initial assessment are twofold: (a) to assess the probability that the patient’s symptoms are related to acute coronary ischemia; and (b) to assess the patient’s risk of recurrent cardiac events, including death and recurrent ischemia (2). In the ideal circumstance, physicians could reliably identify patients with definite ACS and begin appropriate therapy as early as possible, as well as distinguish those without acute coronary ischemia who may be candidates for early discharge without extended observation in the emergency department, chest pain unit, or inpatient wards. Unfortunately, other than in the ∼15% of patients with ACS who present with diagnostic ST-segment elevation, our basic clinical tools (history, physical exam, and electrocardiogram) for making the diagnosis of ACS offer limited sensitivity and specificity. Biomarkers of myocardial necrosis add importantly to these other clinical tools and are a critical component of the assessment of suspected ACS (4). In particular, …