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.