[Value of serum myoglobin in acute myocardial infarction. Kinetic study]

The rise in serum myoglobin (MGB), total CPK (CKT) and its MB isoenzyme (CK - MB) was studied and compared over the first three days of acute myocardial infarction (AMI) and correlations were sought between the peak values of these three parameters and haemodynamic and biological indices of left ventricular function. Blood was taken from MGB (radio immunological technique), CKT and CK - MB (spectrophotometry) estimation every 2 hours for 24 hours and then every 6 hours up to the 72nd hour in 36 patients with AMI less than 12 hours old. On admission, this protocol was completed by a haemodynamic study (right heart pressures, systemic blood pressure, cardiac output measurement by thermodilution), arterial gases and ECG recordings. The average delays before the pathological rise, the maximal peak value and the return to normal were significantly shorter (p less than 0.001) for MGB (2, 6 and 25 hours) than for CK - MB (5,16 and 34 hours) or CKT (5,21 and 57 hours). The sensitivity of the diagnosis of myocardial infarction was not significantly higher with MGB than CKT or CK - MB either in the whole group (sensitivity of 91.6 p. 100 for MGB and 86.1 p. 100 for CKT and CK - MB) or in a subgroup of ten patients without transmural infarction (70 p. 100 for MGB compared with 60 p. 100 for CKT and CK - MB). A significant correlation was found between the peak values of MGB (p less than 0.02) and CK- MB (p less than 0.02) and the indices of left ventricular function (PCP, PAO2 and LVSWI). This was not observed with CKT. In conclusion, apart form technical problems which remain unresolved time-consuming investigation), serum MGB gives a much earlier and as sensitive a biochemical diagnosis of AMI as CKT and CK - MB. MGB and CK - MB are much better prognostic indicators than CKT as judged by the indices of left ventricular function. Finally, MGB estimation should be of particular value in the diagnosis of secondary extension of infarction.