Background: A rapid, accurate, noninvasive means of predicting the likelihood of failure to achieve Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow within 90 minutes after the start of fibrinolysis with streptokinase could help to identify patients who might benefit from additional therapies that aim to preserve myocytes.
Methods: We measured ST recovery, which was assessed as the sum of ST deviation on a 12-lead electrocardiogram, and blood levels of the myocardial proteins, troponin T, creatine kinase myocardial band (CK-MB), and myoglobin before and 60 minutes after commencing streptokinase infused for 30 to 60 minutes in 107 patients, who presented within 12 hours of symptom onset and underwent angiography at 90 minutes.
Results: At 90 minutes, 56% of patients (95% CI 46-66) had TIMI-3 flow. The baseline levels of troponin T, CK-MB, and myoglobin were more commonly below the discrimination values in patients with TIMI-3 flow than in patients without TIMI-3 flow (all P <.005). On multivariate analysis, the factors associated with failure to achieve TIMI-3 flow were ST recovery of <70% (P =.009), a 60-minute/baseline troponin T ratio of < or =5 (P =.0004), a baseline CK-MB level of >4 microg/L (P =.039), or a baseline myoglobin level of >85 microg/L (P =.048). Age and a history of myocardial infarction were added into the multivariate model, and a risk score was developed to predict the likelihood of failure to achieve TIMI-3 flow. A score of < or =2 excluded failure to achieve TIMI-3 flow with 96% accuracy, and a score of > or =7 predicted failure to achieve TIMI-3 flow with 90% accuracy.
Conclusion: Failure to achieve TIMI-3 flow in the infarct-related artery within 90 minutes after the start of fibrinolysis can be accurately predicted at approximately 60 minutes by a score incorporating clinical variables, ST recovery, and the 60-minute/baseline ratios of troponin T, CK-MB, and/or myoglobin levels. This score may facilitate triage of patients at 60 minutes after fibrinolysis to additional reperfusion therapies.