Diagnostic Performance of Quantitative Flow Ratio (QFR) Values Generated from Automatic TIMI Frame-Counting

Abstract

Background: QFR (quantitative flow ratio) is a computational measurement of FFR (fractional flow reserve), calculated from coronary angiography. Latest QFR software automates TIMI frame counting (TFC), which occurs during the flow step of QFR analyses, making the analysis faster and more reproducible. The objective is to determine the diagnostic performance of QFR values obtained from analyses using automatic TFC compared to those obtained from analyses using manual TFC, in the assessment of hemodynamically significant coronary lesions. Methods and Results: This was a single-arm clinical trial that used the prospective analysis of retrospective data to compare the automatic and current gold standard manual TFC QFR values of 97 patients who underwent coronary angiography. The diagnostic performance of automatic TFC QFR values was measured as follows: sensitivity was 0.8696 (95% CI 0.6641–0.9722) and specificity was 1.00 (95% CI 0.9514-1.00), positive predictive value (PPV) was 1.00 (95%CI 1.00–1.00), while the NPV was 0.9610 (95% CI 0.9610–0.9936). Overall accuracy was 96.91% (95% CI 91.23%-99.36%). The agreement as illustrated by the Bland-Altman plot shows a bias of 0.0023 (SD 0.0208) and narrow limits of agreement (LOA): Upper LOA 0.0573 and Lower LOA − 0.0528. The area under curve (AUC) was 0.996. Conclusions: QFR values generated from automatic TFC are comparable to those generated from manual TFC in diagnostic capability. The most recent software update is equivalent to the previous manual option and therefore it can be used interchangeably.