Cardiac Troponin T to evaluate myocardial protection via intermittent coldblood or continuous warm blood cardioplegia in coronary artery bypass grafting

Background The aim of our study was to evaluate the efficacy of myocardial protection during coronary artery bypass grafting (CABG) in cold blood inte rmittent (CBIC) and warm continuous blood cardioplegia (WCBC), To assess my ocardial necrosis, Troponin T, a structural protein belonging to the tropon in complex, was measured. Troponin T is released in the blood stream 4 hour s after myocardial damage, and it does not cross-react with the isomeric fo rm of the skeletal muscle. Methods. Our study involved 20 consecutive patients, scheduled for isolated CABG. They were divided into two groups: the first group (10 patients; 8 m , 2 f) underwent surgery with the use of CBIC, the second group (10 patient s; 9 m, 1 f) with WCBC. The serum levels of cardiac Troponin T (cTn-T) were all <0.2 mu g/l before operation. Results. In the CBIC the mean cTn-T peaked on the 1st day after CABG, in th e WCBC group the first peak occurred in the 2nd hour after arrival in the i ntensive care unit, and the second peak occurred on the 4th day postoperati vely. The mean serum cTn-T was lower in the WCBC vs CBIC group from the Ist to the 5th day postoperatively, with a statistical difference on the Ist d ay (p<0.05). In the CBIC group either the cTn-T peak values (r=0.77; p<0.02 ) or area under the concentration curve of cTn-T release (r=0.85; p<0.004), were directly correlated with the aortic cross-clamping time. This was not demonstrated in the WCBC. CPK and CK-MB peaked in both groups 6 hours afte r arrival in the intensive care unit and on the Ist day postoperatively, wi th higher values at 6 hours in the WCBC group (p<0.05). The CK-MB/CPK ratio was significantly lower in the WCBC group at the six hours (p<0.05). Conclusions. The results of this preliminary study suggest that fewer necro sis markers are released during CABG in the WCBC group; in the CBIC group t he release of cTn-T whether measured by peak serum level or by area under t he curve, shows a statistically significant correlation with cross-clamping time, Warm blood cardioplegia is safe and supplies adequate myocardial pro tection during CABG; the more prolonged cross-clamping is, the more myocard ial protection is afforded by WCBC.