A score predicts failure of reperfusion after fibrinolytic therapy for acute myocardial infarction.
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.


CONCLUSIONS
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.
French
John K
JK
Cardiology Department, Green Lane Hospital, Auckland, New Zealand, Montréal Heart Institute, Montréal, Québec, Canada. johnf@adhb.govt.nz
Ramanathan
Krishnan
K
Stewart
James T
JT
Gao
Wanzhen
W
Théroux
Pierre
P
White
Harvey D
HD
D015415:Biomarkers / Q000097:blood; D003326:Coronary Circulation / Q000187:drug effects*; D003402:Creatine Kinase / Q000097:blood; D052279:Creatine Kinase, MB Form; D004562:Electrocardiography / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D015425:Myocardial Reperfusion / Q000706:statistics & numerical data*; D009211:Myoglobin / Q000097:blood; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013300:Streptokinase / Q000494:pharmacology / Q000627:therapeutic use*; D015912:Thrombolytic Therapy; D013997:Time Factors; D017211:Treatment Failure; D020107:Troponin T / Q000097:blood
D015415:Biomarkers; D007527:Isoenzymes; D009211:Myoglobin; D020107:Troponin T; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form; D013300:Streptokinase