Myocardial oxidative stress, and cell injury comparing three different techniques for coronary artery bypass grafting

Abstract

Oxidative stress as a result of reperfusion injury is a known causative factor of cardiac muscle injury. In the peripheral blood as well in the coronary sinus, oxidative stress parameters and cardiac biomarkers were measured to investigate the different levels of oxidative stress during three different CABG techniques; MCABG (with minimal prime volume and warm blood cardioplegia) that was newly introduced in our hospital, versus OPCAB, versus our current standard, conventional CABG (CCABG, consisting of high volume prime and cold crystalloid cardioplegia). Concomitantly, cardiac biomarkers were measured to detect myocardial cell injury. Thirty patients scheduled for CABG with the intention to treat three-vessel disease were randomly assigned for CCABG, MCABG or OPCAB. Perioperatively, plasma levels of malondialdehyde (MDA) as a marker of oxidative stress, and the allantoin/uric acid ratio (A/U ratio) as a marker of antioxidant activity were measured in the ascending aorta (Aa), and in the coronary sinus (Cs), simultaneously. Additionally peripheral (Aa) blood levels of heart fatty acid binding protein (HFABP), troponin T, CPK and CKMB as markers of myocardial injury were obtained. The MCABG group had significantly lower MDA levels in the Cs compared to the CCABG group, respectively, to the OPCAB group (p=0.04 and p=0.03). At all time points the A/U ratio in the CCABG group remained significantly higher in the Cs as well in the Aa samples compared to the MCABG and the OPCAB group (p<0.001, respectively, p<0.001, for both groups). HFABP and troponin T showed consistent curves compared to the CPK figure over time in all groups. In this study coronary sinus blood levels of oxidative stress parameters were consistently higher compared to peripheral blood levels. The levels were lowest in the MCABG study group. In this group also the lowest levels cardiac biomarkers of myocardial injury were found.