Abstract 9140: Validity of Coronary Angiography-Based Physiology in Clinical Practice

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Introduction: The invasive physiological assessment of the severity of coronary obstruction is performed by hyperemic (FFR) and non-hyperemic (iFR) indices. However, the need to insert an intracoronary pressure guidewire are factors that limit its use. Quantitative flow ratio (QFR) is a method that infers the value of FFR, eliminating the use of a pressure wire and coronary hyperemia. Objectives: Evaluate the diagnostic accuracy of the QFR, diameter stenosis percentual (DS%) and area stenosis percentual (AS%) in comparison with the FFR, for identification of significant obstructive coronary lesions (FFR ≤ 0.80) and the feasibility to assess QFR in cohort of patients without dedicated angiographic acquisition. Methods: Consecutive patients with moderate obstructive lesions in coronary angiography that had previous FFR measurement were evaluated. Validation of QFR was assessed by accuracy, area under the curve (AUC), sensitivity, specificity, correlation coefficient and Bland-Altman plot, using FFR as reference method. Results: Out of 102 patients and 143 arteries assessed by the FFR, only 69 (67%) patients and 75 (52%) arteries were possible to be calculated by QFR. The accuracy of the QFR to detect an FFR ≤ 0.80 was 84.0% (95% CI: 75.6% to 92.4%), with a sensitivity of 67.9% (95% CI: 47.6% to 84.1%) and specificity of 93.6% (95% CI: 82.5% to 98.7%). The correlation and agreement between FFR and QFR were r = 0.54, p < 0.01 and mean difference = -0.02 ± 0.09; p = 0.0874, respectively. The AUC to QFR, DS% and AS% comparison are represented in the attached figure. Conclusions: QFR demonstrated good accuracy and agreement, compared to the FFR, with moderate correlation in an unselected population of clinical practice. QFR and DS% demonstrated AUC greater than AS%. However, the high rate of exclusion in offline evaluations of angiograms recorded without dedicated acquisition protocol considerably limits the use of this tool in clinical practice.