The Relationship between Thrombolysis in Myocardial Infarction Frame Count and Fractional Flow Reserve in Patients with Moderate Coronary Stenosis Undergoing Coronary Angiography

Thrombolysis in myocardial infarction (TIMI) frame count (TFC) is an objective and quantitative index of coronary flow, and myocardial fractional flow reserve (FFR) is a lesion-specific index for epicardial coronary stenosis. Currently, FFR is the most valid tool for decision making in coronary interventions. However, it incurs relatively high costs and it is not reimbursed by the insurance companies in Iran. In this study, we aimed to determine the relationship between corrected TFC (CTFC) and FFR in patients who are simultaneously undergoing coronary angiography and FFR measurement for moderate coronary artery lesions.
This retrospective cross-sectional study was performed on 24 patients (16 males and 8 females) with the mean age of 57.7 years who underwent FFR for moderate coronary stenosis. Patients with recent myocardial infarction, coronary ectasia, and slow flow coronary syndrome were excluded. FFR was determined by measuring the mean coronary pressure distal to the stenosis and comparison with the mean aortic pressure using a pressure wire. On the other hand, the first frame used for TFC was defined by a column of contrast extending across more than 70% of the arterial lumen and the last frame count was one in which contrast first appeared in the distal, pre-defined landmark branch for the coronary artery of interest. CTFC was calculated for the left anterior descending (LAD) coronary artery by dividing TFC of the LAD by a factor of 1.7.
Fifteen patients had LAD, seven had right coronary artery, and two had left circumflex lesions. The mean values for CTFC and FFR were 20.6 and 0.90, respectively. There was not a statistically significant correlation between FFR and CTFC (r=0.14; P=0.514).
Given that there is no significant correlation between CTFC and FFR, CTFC cannot be used as an independent index for decision making in coronary artery interventions.