A STUDY OF BIOCHEMICAL MARKERS OF REPERFUSION EARLY AFTER THROMBOLYSIS FOR ACUTE MYOCARDIAL-INFARCTION

Background In acute myocardial infarction (AMI), early noninvasive ide ntification of patients with occluded infarct-related arteries (IRAs) after thrombolysis has important prognostic and therapeutic implicatio ns. The aims of this study were to evaluate biochemical methods for th e early diagnosis of patency after thrombolysis prospectively and to e stablish the optimal diagnostic criteria retrospectively. Methods and Results In 97 patients with AMI treated with thrombolytic agents less than or equal to 6 hours after the onset of symptoms, myoglobin, tropo nin T, creatine kinase, the MB isoenzyme and MM isoforms of creatine k inase were measured just before thrombolysis began and 90 minutes late r. IRA patency was assessed by means of 90-minute coronary angiography . For each marker, compared with the expected sensitivity and specific ity based on published thresholds for the diagnosis of patency, the ob served values were consistently lower but were markedly improved in a subset of patients treated >3 hours after the onset of symptoms. With receiver-operator characteristic curve analysis of the slopes of incre ase and relative increases in each marker over 90 minutes, the best di agnostic performance was achieved by use of the relative increase in m yoglobin, troponin T, and MM3/MM1 creatine kinase isoforms in patients treated >3 hours after onset (areas under the curve of 0.84, 0.83, an d 0.85, respectively).Conclusions Effective early noninvasive diagnosi s of patency after thrombolysis is possible in patients treated >3 hou rs after symptom onset by use of criteria derived from the relative in crease over 90 minutes in plasma markers, particularly myoglobin, trop onin T, and MM3/MM1 creatine kinase isoforms. The diagnostic performan ce of the relative increase in myoglobin appears to be less susceptibl e to small changes in the diagnostic threshold value.