Assessment of myocardial damage by circulating cardiac myosin light chain I after heart transplantation.

The purpose of this study was to evaluate the cardiac damage by cardiac myosin light chain I after transplantation. This study included 30 patients who underwent cardiac operations and who were divided into three groups. These groups consisted of (1) control group, 15 valvular patients without coronary disease (no electrocardiography changes and creatine kinase MB isoenzyme of 100 micrograms/L or less); (2) infarction group, eight patients (six coronary bypass and two valvular patients with perioperative infarction pattern in the electrocardiography and creatine kinase MB isoenzyme of 100 micrograms/L or more; and (3) transplantation group, seven transplant patients (six heart and one heart-lung). The peak cardiac myosin light chain I value in the transplantation group (32.9 +/- 3.4 micrograms/L) was comparable to the infarction group (27.6 +/- 2.6 micrograms/L), and both of them were significantly higher than the control group (9.2 +/- 0.9 micrograms/L) (p < 0.01). Peak cardiac myosin light chain I levels in the control and transplantation groups correlated with the ischemic time (r = 0.48, p < 0.05 and r = 0.67, p < 0.05, respectively). The total dose of dopamine in the transplantation group correlated with the peak cardiac myosin light chain I (r = 0.67, p < 0.05), and with the cardiac myosin light chain I value on day 7 (r = 0.88, p < 0.01). This study suggests that circulating cardiac myosin light chain I estimations are useful to evaluate myocardial damage after transplantation during postoperative week 1.