The superiority of TIMI frame count in detecting coronary flow changes after coronary stenting compared to TIMI Flow Classification.

AIMS: We compared the qualitative Thombolysis in Myocardial Infarction (TIMI) Flow Classification with a new quantitative method, the TIMI Frame Count, to investigate the differences of both systems in detecting coronary flow changes after stent implantation.
METHODS: TIMI flow grades and corrected TIMI frame counts (CTFC) were determined in 102 patients before, after stent implantation and at 6-month angiography. Analysis of the CTFC in patients with TIMI flow grades 3 and 2 demonstrated that for CTFC values lower than 30 frames, all patients had TIMI flow grade 3, while for CTFC values greater than 69 frames no patient had TIMI grade 3 flow. For CTFC values between 30 and 69 frames, TIMI grades 3 and 2 flow overlap. Comparing changes in TIMI flow grades and the CTFC before and after stent implantation (after stent implantation and at 6 month angiography), CTFC detects flow changes in 46% (40%) of the patients, which were not detected with TIMI Flow Classification.
CONCLUSION: The TIMI Flow Classification grading system is not able to separate clearly between completely perfused and partially perfused coronary artery vessels. The quantitative TIMI Frame Count method is superior to the qualitative TIMI Flow Classification in detecting coronary flow changes.