MYOGLOBIN AND CPK-MM ISOFORMS DURING ACUT E MYOCARDIAL-INFARCTION

The biological diagnosis is usually late with respect to clinical and electrocardiographic signs of acute myocardial infarction. Recent labo ratory methods have stimulated renewed interest in very early marker o f infarction : myoglobin and CPK isoforms. The authors undertook a pro spective study of the diagnostic sensitivity of myoglobin (MG), CPK an d CPK-MM isoforms in 30 consecutive patients undergoing intravenous th rombolytic therapy in the acute phase of myocardial infarction. Blood samples were obtained on admission and every 30 minutes for 1 h 30. Th e Mb contributed to diagnosis of infarction on admission in 89 % of pa tients. This percentage fell to 44 % for the ratio MM3/MM1 > 0.5 to 27 % for the CPK and to 24 % for the ratio MM3/MM1 > 1. The sensitivity of all tests increased in the later blood samples but it remained low in the CPK and MM3/MM1 > 1 criteria. The diagnostic sensitivity of the first sample was also better in patients admitted after the 3rd hour (Mb = 100 %; MM3/MM1 > 0.5: 58 %; CPK: 41 %) compared with those admit ted before the 3rd hour (Mb = 82 %; MM3/MM1 > 0.5: 35 %; CPK: 17 %). T hese results show that the diagnostic sensitivity of biological marker s of myocardial infarction is very different. The serum myoglobin is a n earlier and more sensitive marker than the CPK or CPK-MM isoforms.