Myoglobin, creatine-kinase-MB and cardiac troponin-I 60-minute ratios predict infarct-related artery patency after thrombolysis for acute myocardial infarction : Results from the thrombolysis in myocardial infarction study (TIMI) 10B

OBJECTIVES We examined the diagnostic performance of serum myoglobin, creatine-kinase-MB (CK-MB) and cardiac Troponin-I (cTnI) for predicting the infarct-related artery (IRA) patency in patients receiving TNK-tissue plasminogen activator (TNK-tPA) therapy for acute myocardial infarction (AMI) in the Thrombolysis in Myocardial Infarction (TIMI) 10B trial. BACKGROUND reliable noninvasive serum marker of IR patency is desired to permit early identification of patients with patent IR after thrombolysis. METHODS We measured myoglobin, CK-MB and cTnI concentrations in ser obtained just before thrombolysis (T0) and 60 min later (T60) in 442 patients given TNK-tP and who underwent coronary angiography at 60 min. RESULTS Angiography at 60 min showed patent IR (TIMI flow grade 2, 3) in 344 and occluded IR (TIMI flow grade 0, 1) in 98 patients. The median serum T60 concentration, the ratio of the T60 and T0 serum concentration (60-min ratio) and the slope of increase over 60 min for each serum marker were significantly higher in patients with patent arteries compared with patients with occluded arteries. The are under the receiver-operating characteristic (ROC) curve for diagnosis of occlusion was 0.71, 0.70 and 0.71 for the 60-min ratio of myoglobin, cTnI and CKMB, respectively. The 60-min ratios of ≥4.0 for myoglobin, ≥3.3 for CK-MB and ≥2.0 for cTnI yielded probability of patency of 90%, 88% and 87%, respectively. CONCLUSIONS The diagnostic performance of serum myoglobin, CK-MB and cardiac Tropinin-I (cTnI) 60-min ratios was similar. The probability of patent IR was very high (90%) in patients with 60-min myoglobin ratio ≥4.0, and early invasive interventions to establish IR patency may not be necessary in this group. Serum marker determinations at baseline and 60-min after thrombolysis may permit rapid triage of patients receiving thrombolytic therapy by ruling out IR occlusion.