Assessment of coronary reperfusion in patients with myocardial infarction using fatty acid binding protein concentrations in plasma

Objective-To examine whether successful coronary reperfusion after thrombol ytic treatment in patients with confirmed acute myocardial infarction can b e diagnosed from the plasma marker fatty acid binding protein (FABP), for e ither acute clinical decision making or retrospective purposes. Design-Retrospective substudy of the GUSTO trial. Setting-10 hospitals in four European countries. Patients-115 patients were treated with thrombolytic agents within six hour s after the onset of acute myocardial infarction. Patency of the infarct re lated artery was determined by angiography within 120 minutes of the start of thrombolysis. Main outcome measures-First hour rate of increase in plasma FABP concentrat ion after thrombolytic treatment, compared with increase in plasma myoglobi n concentration and creatine kinase isoenzyme MB (CK-MB) activity. Infarct size was estimated from the cumulative release of the enzyme a hydroxybutyr ate dehydrogenase in plasma during 72 hours, or from the sum of ST segment elevations on admission. Logistic regression analyses were performed to con struct predictive models for patency. Results-Complete reperfusion (TIMI 3) occurred in 50 patients, partial repe rfusion (TIMI 2) in 36, and no reperfusion (TIMI 0+1) in 29. Receiver opera ting characteristic (ROC) curve analyses showed that the best performance o f FABP was obtained when TIMI scores 2 and 3 were grouped and compared with TIMI score 0+1. The performance of FABP as a reperfusion marker was improv ed by combining it with a hydroxybutyrate dehydrogenase infarct size, but n ot with an early surrogate of infarct size (ST segment elevation on admissi on). In combination with infarct size FABP performed as well as myoglobin ( areas under the ROC curve 0.868 and 0.857, respectively) and better than CK -MB (area 0.796). At optimum cut off levels, positive predictive values wer e 97% for FABP, 95% for myoglobin, and 89% for CK-MB (without infarct size, 87%, 88%, and 87%, respectively), and negative predictive values were 55%, 52%, and 50%, respectively (without infarct size, 44%, 42%, and 34%). Conclusions-FABP and myoglobin perform equally well as reperfusion markers, and successful reperfusion can be assessed, with positive predictive value s of 87% and 88%, or even 97% and 95% when infarct size is also taken into account. However, identification of non-reperfused patients remains a probl em, as negative predictive values will generally remain below 70%.