Biochemical estimation of infarct size

The measurement of cardiac troponin (cTn), as cardiac troponin T (cTnT) or cardiac troponin I (cTnI), is now the accepted ‘gold standard’ biomarker for myocardial injury and forms part of the diagnostic criteria for acute myocardial infarction.1 The measurement of cTn is part of the diagnostic workup in all patients with suspected acute coronary syndrome, but does it also play a role in defining the extent of myocardial injury and if so for what purpose? The rationale for the assessment of infarct size comes from the assumption that the degree of myocardial dysfunction post-myocardial infarction will depend on the magnitude of cardiac injury. This is certainly true but there are caveats. Residual myocardial function will also depend on previous myocardial injury, the site of infarction and the degree of peri-infarct dysfunction due to myocardial stunning. Cardiac biomarker measurement occurs in the majority of patients as part of the diagnostic routine so information on infarct size will be available as an added bonus. Measurement of the cytoplasmic biomarkers of myocardial injury, myoglobin,2 creatine kinase (CK) …