Measurement of myosin light chain I and troponin T as markers of myocardial damage after cardiac surgery.

The purpose of the study was to test cardiac myosin light chain I (CMLCI) and troponin T (TNT) as markers on myocardial damage after heart surgery. Forty-three patients undergoing cardiac surgery were arbitrarily divided into two groups according to creatine kinase MB isoenzyme (CK-MB) levels and postoperative electrocardiogram (ECG) changes. Group 1: CK-MB > 100 micrograms/L or ECG changes (extensive myocardial damage, 42%); Group 2: CK-MB < 100 micrograms/L and no ECG changes (minimal myocardial damage, 58%). Group 1 was divided into 2 groups (Infarction and Injury groups). CMLCI levels showed strong correlations with TNT levels after the operation. The peak CMLCI and TNT levels in group 1 were significantly higher than in group 2. The peak CMLCI in the Infarction group was significantly higher than in the Injury group. TNT showed different patterns in the Infarction and Injury groups. This study showed that CMLCI and TNT estimation could evaluate myocardial damage over several postoperative days. TNT estimation could identify myocardial damage earlier than CMLCI, however CMLCI could discriminate perioperative infarction better than TNT.