Biomarkers of myocardial protection
Laboratory parameters such as high sensitivity cardiac troponin I (cTnI),T (cTnT) and CK-MB are indispensable biomarkers utilised to define myocardial injury and predict prognosis amongst patients undergoing cardiac surgery(43-45). cTnI is a gold-standard necrotic biomarker used for risk assessment post-cardiac surgery as it is released almost exclusively in the myocardium in the presence of myocardial injury irrespective of the mechanism of injury(46). Importantly, the release of cTnI post-cardiac surgery was found to be associated with increased mortality and morbidity(47). cTnI elevation after cardiac surgery indicates multifactorial peri-operative myocardial injury, and it may be used as a biomarker reflecting cumulative intraoperative adverse effects on the myocardium(48). CK-MB activity is also a valuable sensitive and specific indicator of reperfusion, myocardial injury, and infarct size, though inferior to cTnI(49).
In addition to cTnI and CKMB, a recent study demonstrated the elevation of the apoptotic biomarker caspase-3 p17 – this reflected that, along with necrosis, apoptosis also occurs during I-R in patients undergoing cardiac surgery with cardioplegia(50). This puts forward a theory that caspase-3 p17 could therefore also be utilised as an indicator of the effectiveness of myocardial protection provided by cardioplegia in cardiac surgery.