Multimarker Approach for Diagnosis of Acute Myocardial Infarction: Better Answers Need Better Questions

Chest pain is the presenting complaint in approximately 5% of all emergency department visits, making chest pain the second most common reason for seeking acute medical care (1). The prevalence of acute myocardial infarction (AMI) in this emergency department population with chest pain ranges from 5% to 15%. Reliable exclusion or confirmation of AMI within the first few hours after presentation still constitutes a diagnostic challenge. Earlier confirmation (rule-in) than is obtainable currently would permit earlier start of appropriate treatment, and earlier exclusion (rule-out) would facilitate early discharge of patients for whom further in-hospital evaluation or treatment is unnecessary. Myocardial infarction is defined as myocardial necrosis of ischemic origin (2). AMI is not a homogenous condition, however. It ranges from minor infarctions with necrosis of less than 1 g of the myocardium to large infarctions of more than one-third of the left ventricular mass. Furthermore, although by definition the cause of the necrosis is ischemia, the causes of the ischemia can range from plaque rupture with an overlying coronary-flow–obstructing thrombosis (type I infarction) to supply/demand imbalance without a thrombotic component (type II, secondary infarction) to iatrogenic causes, e.g., associated with percutaneous coronary intervention or coronary artery bypass grafting procedures (type IV and V infarctions). Thus, the challenge to find biochemical markers useful for diagnosis of AMI remains fundamentally important.