Characteristics of creatine release during acute myocardial infarction, unstable angina, and cardiac surgery.

Creatine release was compared in various conditions of muscle damage: acute myocardial infarction (AMI), unstable angina, and cardiac surgery. After AMI, serum and urine creatine concentrations increased transiently. After cardiopulmonary resuscitation, serum creatine values were significantly higher because of impaired renal function, whereas urinary creatine concentrations were comparable. In 38 patients with unstable angina, no significant changes in serum and urine creatine concentrations were seen. In 37 of 92 AMI patients, secondary creatine peaks were observed 20.9 +/- 8.1 h after onset of symptoms. The magnitudes of the first and second peaks were correlated: Spearman r = 0.66. In 24 patients who underwent cardiac surgery, the changes in creatine concentration in serum during surgery were very small, despite the presence of muscle trauma.

Acute myocardial infarction size and myoglobin release into serum.

The kinetics of myoglobin release after acute myocardial infarction were studied. Various algorithms for calculation of infarct size, based on immunonephelometric determination of myoglobin and cumulative myoglobin release into the circulation were compared. The cumulative myoglobin release and maximal serum myoglobin concentration were compared with various measures of infarct size: cumulative release of creatine kinase, electrocardiographic changes, and left ventricular ejection fraction. After acute myocardial infarction, time to peak for myoglobin in serum was correlated with time to peak for creatine kinase (r = 0.645). On average, the myoglobin concentration peaked 8.8 h earlier than creatine kinase activity. The rate of elimination of myoglobin showed a large variation (0.041-0.628 h-1) and was not correlated with the elimination rate of creatine kinase. The elimination rate of myoglobin after acute myocardial infarction was shown to depend on the patient's age and infarct size. The elimination constant of myoglobin is preferably estimated on an individual basis in large and complicated infarctions. Cumulative myoglobin release correlated with algorithms based on the cumulative release of creatine kinase (r = 0.622) and its isoenzyme MB (r = 0.660), and to a lesser extent with the residual left ventricular ejection fraction (r = 0.513) and the sum of ST-segment deviations on electrocardiography (r = 0.469). Maximal myoglobin values in serum correlated moderately with the calculated infarct size (r = 0.488; based on creatine kinase-MB) and electrocardiographic changes (r = 0.554). In combination with fast immunological methods for myoglobin determination, myoglobin peak height offers the advantage of providing reliable results within 12 h after onset of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)