National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines: Clinical Characteristics and Utilization of Biochemical Markers in Acute Coronary Syndromes

### a. definition of terms Acute coronary syndrome (ACS)1 refers to a constellation of clinical symptoms caused by acute myocardial ischemia (1)(2). Owing to their higher risk for cardiac death or ischemic complications, patients with ACS must be identified among the estimated 8 million patients with nontraumatic chest symptoms presenting for emergency evaluation each year in the US (3). In practice, the terms suspected or possible ACS are often used by medical personnel early in the process of evaluation to describe patients for whom the symptom complex is consistent with ACS but the diagnosis has not yet been conclusively established (1). Patients with ACS are subdivided into 2 major categories based on the 12-lead electrocardiogram (ECG) at presentation (Fig. 1⇓ ): those with new ST-segment …