[Value of mass dosage of the MB isoenzyme of creatinine phosphokinase in the diagnosis of recent myocardial infarction].

In 391 patients admitted 3.7 hours (h) (median) after experiencing infarct-like pain, kinetic monitoring of CK-MB "mass" (threshold: 7 micrograms/l), myoglobin (threshold: 90 micrograms/l) and total CK (threshold: 290 micrograms/l) was carried out at the time of admission and after 1.5, 3, 6, 9, 12, 24 and 48 h. When myocardial infarction (MI) was treated conventionally (102 patients). CK-MB peaked 11 h (median) after the onset of pain, later than myoglobin (9 h), but before total CK (12 h). The peak of the markers was higher in Q+ than in Q-MI (p < 0.05). When MI was treated by thrombolytic medications (44 patients), the increases in CK-MB, myoglobin and total CK were larger, and occurred sooner (peaks 9, 6 and 6 h, after the onset of pain respectively), but did not last as long. In 245 patients who had not had MI (including 123 with spontaneous angina), the levels of the three markers remained stable and well below the decision thresholds. The sensitivities of CK-MB, myoglobin and total CK were respectively 47.1, 51.8 and 34.8% at the time of admission, 67.3, 82.7 and 57.1% after 3 h and 83.1, 76.9 and 88.9% after 6 h. The combined determination of CK-MB and of myoglobin had a higher sensitivity (67.7% at the time of admission, 84.9% after 1.5% and 88.2% after 3 h: but most of this gain was due to myoglobin. The specificity of the three markers and their diagnostic accuracy are comparable. In the course of recent MI, the kinetics of CK-MB mass are thus slower than those of myoglobin, but a little faster than those of total CK. The choice of the most effective biochemical marker depends upon the interval between onset of chest pain and hospitalization of the patient. Repetition of the determinations improves the diagnostic situation.