Postoperative changes in myosin light chain and comparison with postoperative clinical variables in patients who have undergone valve surgery.

We measured the levels of creatine kinase-MB (CK-MB) and myosin light chain (MLCI) in 86 patients after double valve replacement to investigate whether measurement of the postoperative changes in myosin could be useful in patients undergoing valve surgery. In particular, we compared the postoperative levels of CK-MB and MLCI with the occurrence of postoperative low cardiac output syndrome (LOS). In both groups of patients (group I: without LOS, group II: with LOS), the peak CK-MB level was observed on postoperative day 1, and the peak myosin level on postoperative day 5. No significant differences were found in the postoperative levels of CK-MB between the two groups. On the other hand, a significant difference in the levels of MLCI on postoperative day 5 was observed (p < 0.05). Our results also showed that the peak level of CK-MB significantly correlated with the cardiopulmonary bypass time (r = 0.50), while the peak level of MLCI was significantly correlated with the postoperative cardiac index (r = -0.45). Our retrospective findings suggest that postoperative measurement of MLCI may be useful for estimating the postoperative myocardial impairment after valve surgery.