Cardiovascular disease is the most common cause of mortality worldwide and a major public health concern, with the majority of cardiovascular deaths attributable to coronary artery disease. Acute coronary syndrome (ACS) is an ominous manifestation of coronary artery disease and a spectrum of myocardial ischemia ranging from angina with reversible tissue damage to myocardial infarction (MI) with tissue necrosis. Timely and accurate diagnosis of ACS is crucial for initiating early treatment and missed diagnosis may have serious consequences. Biochemical cardiac markers include proteins released from the injured myocardium into the circulation and have long been used for aiding in the diagnosis and risk stratification of ACS. Over the past decades, cardiac biomarkers have evolved greatly from the earlier markers with less myocardium selectivity to later highly cardiac‐specific markers. In addition, the advance in technology has allowed for continuing improvement of analytical sensitivity of cardiac biomarker assays. The increased sensitivity has revolutionized ACS diagnosis by facilitating earlier detection of biomarker rise, shorter time intervals for serial measurements, and faster patient triage in emergency departments.
This chapter describes the current definition of MI and its latest diagnostic guidelines, with a focus on cardiac troponin and the new generation of high‐sensitivity cardiac troponin (hs‐cTn) assays as the preferred cardiac marker. Development of optimal diagnostic algorithms, factors affecting the performance of these algorithms, and alternative diagnostic protocols are discussed. In addition, historical cardiac markers and novel markers with their potential advantages are reviewed.