COMPARISON OF 2 STRATEGIES FOR MYOCARDIAL MANAGEMENT DURING CORONARY-ARTERY OPERATIONS

Despite the current trend for using blood cardioplegia, ventricular fi brillation with intermittent ischemia is still used as a strategy to m anage the myocardium with impressive results. These two methods of myo cardial management were compared in 40 patients undergoing elective co ronary artery operations using creatine kinase MB isoforms and troponi n T assays. Each patient was randomized to have either cold blood card ioplegia (n = 20) or ventricular fibrillation with intermittent ischem ia (n = 20) for myocardial management during the construction of dista l anastomoses. Until recently, the comparison of different methods of myocardial management has been hindered by the lack of a specific and sensitive marker of myocardial damage. Analysis of creatine kinase MB isoforms (MB2, cardiac tissue form; MB1, plasma-modified form) and car diac-specific troponin T (a structural protein) has been shown to impr ove the sensitivity for the detection of myocardial damage. There were no significant differences between the two groups in age, sex ratio, extent of disease, or left ventricular function. Blood samples for ana lysis were collected before cross-clamp application and at time interv als up to 48 hours after. Median peak creatine kinase MB2 activity was found to be significantly higher in the blood cardioplegia group comp ared with ventricular fibrillation (26.5 U/L versus 19.5 U/L, respecti vely, p = 0.04). Although median peak troponin T concentration was hig her in the blood cardioplegia group, the difference failed to reach si gnificance (2.2 ng/mL versus 1.6 ng/mL, p = 0.15). The area under the time-activity curves (a reflection of total release) constructed for c reatine kinase MB, MB2, and troponin T were not significantly differen t between the groups (p = 0.51, 0.82, and 0.31, respectively). These r esults suggest that, for elective coronary artery operations, ventricu lar fibrillation is as effective a strategy to manage the myocardium a s blood cardioplegia and it may even be superior.