Agreement between iFR and other non-hyperaemic pressure ratios in severe aortic stenosis

Andrea Comella, Jasmine Chan, Harsh V. Thakkar, Jiwon Kim, Michael Michail, Stephen J. Nicholls, Robert Gooley, Brian Ko, James D. Cameron, Adam J. Brown

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3 Citations (Scopus)


Background: Instantaneous wave-free ratio (iFR) can reliably assess the physiological significance of coronary artery disease (CAD). Previous studies have demonstrated its interchangeability with other non-hyperaemic pressure ratios (NHPR), but there is no data exploring whether this association is maintained in patients with severe aortic stenosis (AS). Methods: Forty-two patients (67 lesions) with severe AS were recruited and underwent invasive pressure-wire assessment. Data were extracted to calculate iFR, resting Pd/Pa, diastolic pressure ratios (DPR and dPR), and Diastolic Hyperaemia-Free Ratio (DFR). iFR was then compared with other NHPR to determine agreement and accuracy. Results: Mean aortic gradient and dimensionless index were 44.3 ± 11.6 mmHg and 0.23 ± 0.04, respectively. Of the 67 vessels, 57% were LAD, 15% LCx, 13% RCA and 12% other. There was strong positive correlation between iFR and all other NHPR, including Pd/Pa (r = 0.91, p < 0.001), DPR (r = 0.99, p < 0.001), dPR (r = 0.97, p < 0.001) and DFR (r = 0.98, p < 0.001). While Bald-Altman analysis demonstrated that Pd/Pa and DFR were numerically different from iFR, ROC analyses demonstrated iFR ≤0.89 was accurately identified by all NHPRs; Pd/Pa (AUC = 0.965, 95% CI [0.928–0.994]), DPR (AUC = 1.000, 95% CI [1.000–1.000]), dPR (AUC = 0.974, 95% CI [0.937–1.000]), DFR (AUC = 0.989, 95% CI [0.968–1.000]). Conclusion: In patients with severe AS, all the included NHPR in this analysis accurately predicted iFR < 0.89. These data should reassure clinicians that use of alternative NHPR to iFR is reasonable when assessing the physiological significance of CAD in patients with severe AS.

Original languageEnglish
Pages (from-to)47-52
Number of pages6
JournalCardiovascular Revascularization Medicine
Publication statusPublished - Aug 2022


  • Aortic stenosis
  • iFR
  • Instantaneous wave-free period
  • NHPR
  • Non-hyperaemic pressure rations

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