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Diagnostic accuracy of quantitative flow ratio for nonculprit intermediate lesions in patients with ST-segment
Emilio Alfonso Rodríguez1, Josep Gómez-Lara1, Ramón López-Palop2
1Servei de Cardiologia, Grup de recerca cardiovascular, Hospital Universitari de Bellvitge, Institut de Recerca Biomèdica de Bellvitge (IDIBELL), Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain.
Introduction And Objectives:
The reliability of quantitative flow ratio (QFR) has been questioned. Our aim was to evaluate the diagnostic accuracy of QFR in intermediate nonculprit lesions during the index ST-segment elevation myocardial infarction (STEMI) procedure compared with positive pressure wire-based fractional flow reserve (FFR ≤0.80) in a staged procedure.
Methods:
This was a substudy of the multicenter, controlled, and randomized VULNERABLE trial, including 428 intermediate nonculprit lesions from 388 consecutive STEMI patients undergoing FFR assessment in a staged procedure between 1 and 60 days. Off-line QFR analyses were performed during both the index and staged procedures. The primary objective was to assess the diagnostic accuracy of index QFR compared with staged positive FFR.
Results:
Angiographic vessel diameter (2.80±0.59 vs 2.91±0.57mm; P<.01), stenosis severity (51.33±8.04% vs 50.54±7.63%; P=.053), and QFR values (0.85±0.09 vs 0.86±0.09; P=.120) showed minimal changes between the index and staged procedures. Moderate concordance was observed between index QFR and staged FFR (kappa index=0.629; intraclass correlation coefficient=0.641). The diagnostic accuracy of index QFR for predicting positive FFR was good (area under the curve=0.825). An index QFR cutoff ≤0.80 showed moderate sensitivity (72%) and excellent specificity (91%). An index QFR ≤0.87 achieved a sensitivity of 86% for detecting lesions with positive FFR, with 55% of lesions presenting QFR ≤0.87 at the index procedure.
Conclusions:
Index QFR demonstrated good diagnostic accuracy for identifying lesions with positive FFR in a staged procedure. However, an index QFR cutoff value of ≤0.80 showed moderate sensitivity and may underdiagnose approximately 3 out of 10 lesions with positive FFR. An index QFR ≤0.87 provided higher sensitivity and may help avoid invasive (staged) procedures in many patients.
