Diagnostic performance of intravascular ultrasound-based fractional flow reserve in evaluating of intermediate left main stenosis

BACKGROUND The recently introduced ultrasonic flow ratio (UFR), is a novel fast computational method to derive fractional flow reserve (FFR) from intravascular ultrasound (IVUS) images. In the present study, we evaluate the diagnostic performance of UFR in patients with intermediate left main (LM) stenosis. METHODS This is a prospective, single center study enrolling consecutive patients with presence of intermediated LM lesions (diameter stenosis of 30%-80% by visual estimation) underwent IVUS and FFR measurement. An independent core laboratory assessed offline UFR and IVUS-derived minimal lumen area (MLA) in a blinded fashion. RESULTS Both UFR and FFR were successfully achieved in 41 LM patients (mean age, 62.0 +/- 9.9 years, 46.3% diabetes). An acceptable correlation between UFR and FFR was identified (r = 0.688, P < 0.0001), with an absolute numerical difference of 0.03 (standard difference: 0.01). The area under the curve (AUC) in diagnosis of physiologically significant coronary stenosis for UFR was 0.94 (95% CI: 0.87-1.01), which was significantly higher than angiographic identified stenosis > 50% (AUC = 0.66, P < 0.001) and numerically higher than IVUS-derived MLA (AUC = 0.82; P = 0.09). Patient level diagnostic accuracy, sensitivity and specificity for UFR to identify FFR = 0.80 was 82.9% (95% CI: 70.2-95.7), 93.1% (95% CI: 82.2-100.0), 58.3% (95% CI: 26.3-90.4), respectively. CONCLUSION In patients with intermediate LM diseases, UFR was proved to be associated with acceptable correlation and high accuracy with pressure wire-based FFR as standard reference. The present study supports the use of UFR for functional evaluation of intermediate LM stenosis.