Delayed time to peak serum myoglobin level as an indicator of cardiac dysfunction following open heart surgery

Postoperative changes in serum myoglobin levels have been studied in 47 patients undergoing open heart surgery. The patients were retrospectively divided into two groups according to the time to peak myoglobin level during reperfusion. In 38 patients, myoglobin levels increased rapidly to a peak within 3 hours after reperfusion, after which it was cleared from the blood (group 1). Contrarily, a rise in myoglobin levels was persistent for 24 hours and its time to peak was greater than 3 hours after reperfusion in nine patients (group 2). There were no differences in preoperative and early reperfusion (within 1 hour of reperfusion) values of myoglobin between the two groups. At 3, 6, and 12 hours of reperfusion, myoglobin levels were significantly greater in group 2: 448 +/- 196 vs 1,149 +/- 900 ng/ml, 359 +/- 172 vs 2,653 +/- 3,179 ng/ml, 184 +/- 95 vs 1,896 +/- 1,387 ng/ml, respectively, p less than 0.0001 in each. The maximum activities of both myoglobin and CK-MB were significantly higher in group 2 (myoglobin-max: 771 +/- 257 vs 3,221 +/- 3,024 ng/ml, p less than 0.0001; CK-MBmax: 107 +/- 60 vs 227 +/- 219 IU/L, p less than 0.005). Five of nine patients in group 2 required post-operative assistance with intra-aortic balloon pumping (p less than 0.0005 compared with one of 38 in group 1) and perioperative myocardial infarction developed in three patients (33.3 percent) in this group (p less than 0.005 compared with 0 percent in group 1). Thus, patients with a delayed peak of serum myoglobin level exhibited detrimental cardiac failure postoperatively. These findings suggest that myocardial injury accelerated by reperfusion following ischemia might progress in these patients.