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The corrected TIMI frame count. The new gold standard?
J K French1, C J Ellis, H D White
1Cardiology Department, Green Lane Hospital, Auckland, New Zealand.
Insights
The corrected TIMI frame count (CTFC) offers a more reproducible measure of infarct artery blood flow after myocardial infarction (MI). Abnormal CTFCs are common and predict reocclusion, suggesting potential advantages over traditional TIMI flow grades.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Biomedical Engineering
Background:
- Thrombolysis in Myocardial Infarction (TIMI) flow grades are standard for assessing infarct-artery reperfusion efficacy.
- Reproducibility issues with TIMI flow grades have emerged with core angiographic laboratories.
- The corrected TIMI frame count (CTFC) was developed to improve reproducibility in quantifying infarct artery blood flow post-myocardial infarction (MI).
Purpose of the Study:
- To evaluate the utility of the corrected TIMI frame count (CTFC) in assessing infarct-artery blood flow.
- To investigate the relationship between CTFC and left ventricular function (LVF).
- To determine if CTFC predicts reocclusion after MI.
Main Methods:
- Utilized CTFC in two studies examining infarct-artery blood flow post-MI.
- In the HERO 1 study, CTFC was measured after thrombolytic therapy and anticoagulation.
- Infarct-artery flow was assessed using CTFC at four weeks and one year post-MI.
Main Results:
- Only 27% of patients in the HERO 1 study had a normal CTFC (< or = 27) at 90-120 minutes.
- Prolonged CTFC (> 27) correlated with more abnormal LVF (mean chord score -2.51 vs -2.06, p=0.02).
- At four weeks post-MI, 43% of patients had normal CTFC; prolonged CTFC predicted increased one-year reocclusion (p=0.001).
Conclusions:
- Corrected TIMI frame counts (CTFCs) are frequently abnormal in patent infarct-related arteries.
- Abnormal CTFCs are predictive of reocclusion after myocardial infarction.
- Prospective trials are needed to determine if CTFC predicts late clinical outcomes better than TIMI flow grade.
Abstract:
Over the last decade Thrombolysis in Myocardial Infarction (TIMI) flow grades have been the gold standard for the assessment of efficacy of infarct-artery reperfusion. However, with the introduction of core angiographic laboratories, the reproducibility of TIMI flow grades has been questioned. The corrected TIMI frame count (CTFC) has been developed as a more reproducible method of quantifying infarct artery blood flow after myocardial infarction (MI). We have utilised the CTFC in two studies to examine infarct-artery blood flow. In the Hirulog in Early Reperfusion and Occlusion (HERO 1) study, the CTFC was measured at 90-120 minutes after administration of aspirin, streptokinase and either Hirulog or heparin. Only 27% of patients had a normal CTFC (< or = 27) in the infarct-related artery. Patients with a prolonged CTFC (> 27) had more abnormal left ventricular function (LVF) as measured by the mean chord score in the 'area at risk' (-2.51 vs -2.06, p = 0.02), on left ventriculography. In a second study, infarct-artery flow was examined four weeks and one year after MI. At four weeks, only 43% of patients with patient infarct-related arteries had a 'normal' CTFC of < or = 27. A prolonged CTFC at four weeks was a univariate predictor of increased reocclusion at one year (p = 0.001). CTFCs are frequently abnormal in patent infarct-related arteries, and predict reocclusion. Whether frame counting is a better predictor of late clinical outcomes than the TIMI flow grade needs to be prospectively examined in large clinical trials.