Measurement of cardiac troponin T and myosin to detect perioperative myocardial damage during coronary surgery

This study evaluated the use of monitoring blood levels of the isoenzyme of creatine phosphokinase, troponin T (tnT) and myosin in the detection of perioperative myocardial damage after coronary artery surgery. Serial blood samples were collected in 24 patients undergoing myocardial revascularization. The patients were retrospectively divided into three groups: group A with no changes in their electrocardiogram; group B showing non-specific signs of perioperative myocardial infarction such as deep and permanent T wave inversion; and group C with definite electrocardiographic signs of perioperative myocardial infarction (new persistent Q-waves and loss of R-waves). Group A (n = 17) demonstrated a mean(s.d.) troponin T peak blood level of 0.64(0.35) ng/ml at 12-24 h after surgery, a myosin peak of 1030(670) mu units/l at 3-6 days afterwards, and a creatine phosphokinase isoenzyme peak of 25.8(10.6) units/l. In group B (n = 5), mean(s.d.) troponin T levels were elevated to a peak of 4.8(3.9) ng/ml 24 h after intervention, while myosin rose to 2074(340) mu units/l 3-6 days after surgery and creatine phosphokinase isoenzyme reached 57.8(38) units/l. Group C (n = 2) had a mean(s.d.) troponin T peak of 4.8(2.6) ng/ml, a myosin peak of 2404(392) mu unit/l and a creatine phosphokinase isoenzyme peak of 88.5(20) units/l. Peak values of troponin T and myosin in groups B and C were statistically different from those in group A (P < 0.001). These results suggest that troponin T and myosin are reliable indicators of perioperative myocardial damage. In particular, troponin T may allow the differentiation of reversible from irreversible myocardial injury.