Development and validation of the fractional flow reserve (FFR) angiographic scoring tool (FAST) to improve the angiographic grading and selection of intermediate lesions that require FFR assessment

Abstract

Background: Visual angiographic assessment of intermediate coronary lesions is poor at determining the functional significance. We sought to identify independent clinical and angiographic parameters associated with stenosis functional significance and applied them in a weighted fractional flow reserve angiographic scoring tool (FAST) to improve intermediate lesion selection for fractional flow reserve (FFR) assessment.

Methods and results: Data from 100 patients with intermediate lesions previously assessed by FFR were retrospectively analyzed, and four independent variables that predicted FFR of less than or equal to 0.8 were identified: quantitative coronary angiography percent diameter stenosis [odds ratio (OR) 1.22, P<0.001], length more than 20 mm (OR 7.6, P=0.004), stenosis haziness (OR 16.6, P=0.005), and multivessel disease (OR 7.8, P=0.019). Applying these variables into the FAST score, we prospectively assessed a further 109 intermediate lesions (prevalence of FFR ≤0.8 was 29% in this validation cohort) and found that FAST was highly discriminative, predicting an FFR of less than or equal to 0.8 with a c-statistic of 0.865 (95% confidence interval 0.793-0.937, P<0.0001). At the optimal cutoff value, FAST score of more than 2 had a negative predictive value of 96.5% and a sensitivity of 93.8%. It would have reduced the pressure wire usage in the validation cohort by 52.3% (57 out of 109 cases), with only two false negatives and associated cost savings.

Conclusion: The FAST score is a simple angiographic assessment tool for intermediate lesions that comprises four angiographic variables. A score of 2 or lower indicates low likelihood of lesion hemodynamic significance.