instant wave-Free Ratio (iFR)

iFR modality
(instant wave-Free Ratio)

Proven outcomes1,2,3 Superior value1,3

Philips' proprietary technology is the only resting index with with outcomes data from more than 4500 patients studied.

Introduction to the iFR modality instant wave-Free Ratio

iFR modality overview

iFR modality wave-free ratio graph

The iFR modality

  • Philips' proprietary instantaneous, trans-lesional pressure ratio measured during the wave-free period
  • Helps assess lesion significance in about five heartbeats without hyperemic agents


Instant wave-Free Ratio:

  • The instantaneous pressure ratio, across a stenosis during the wave-free period, when resistance is naturally constant and minimized in the cardiac cycle
Wave-free period1

Physiology fundamentals

ifr modality physiology fundamentals

When resistance is constant, changes in pressure are proportional to changes in flow

  • The FFR modality uses hyperemic agents to achieve a state of constant resistance.
  • The iFR modality uses a period of the cardiac cycle when resistance is naturally constant.

Wave-free period

iFR wave-free period graph
Pressure, resistance, and intensity during the wave-free period2

Benefits of the wave-free period

  • Noise from compression and suction waves is minimized.
  • Resistance is constant so △P is proportional to △Q (flow).
  • Velocity is higher so better power to discriminate.

Case example: iFR modality with Verrata pressure guide wire in multi-vessel disease

iFR clinical case

Imperial College, London - February 2014

Simplifying workflow

The iFR modality provides a hyperemia-free measurement in as few as five heartbeats

iFR modality demo screen

Same wire, same system, fewer steps

iFR workflow

Outcomes proven


An iFR cut-point of 0.89, single dichotomous cut-point, backed by data.1,2,6

iFR cutpoint
An iFR cut-point of 0.89 matches best with an FFR ischemic cut-point of 0.80 with a specificity of 87.8% and sensitivity of 73.0%. (From ADVISE II, and iFR Operator’s Manual 505-0101.23)
Both DEFINE FLAIR and iFR Swedeheart were designed with the dichotomous cut-point of iFR in the iFR arm. With comparable MACE rates, these results mean the 0.89 cutpoint for iFR is proven and backed by more than 4500 patients of outcome.1,2

Providing choice

The Verrata Plus pressure guide wire

Verrata pressure guide wire

One wire, one system, multi-modality


New in-line clip connector for improved work flow

• New high fidelity sensor for reliable pressure measurement

• Reliably connect and disconnect with confidence

• Seamlessly switch between FFR and iFR, the only resting index with over 4500 patients studied

An iFR of 0.89 is equivalent to an FFR of 0.801,2,6

iFR modality FFR screen

Fractional flow reserve


  • Clinically proven for ischemia detection.8
  • Supported by multiple society guidelines worldwide.
iFR modality iFR screen

The iFR modality


  • Philips' proprietary instantaneous, trans-lesional pressure ratio measured during the wave-free period.
  • Prospectively tested in the ADVISE II Study.
  • Patient outcome data from the DEFINE FLAIR and iFR Swedeheart trials, published in the New England Journal of Medicine, and validated with 0.89 cut-point patient outcomes.1,2
  • Recent study showed a reduction in costs per patients using
  • iFR-guided strategy3
  • Included in the Appropriate Use Criteria (AUC)8 the National
  • Cardiovascular Data Registry (NCDR)9 and designated as “Definitely
  • Beneficial” by the Society of Cardic Angiography and Interventions
  • (SCAI)."10
  • Included in the European Society of Cardiology (ESC) guidelines as a
  • Class IA recommendation11

ADVISE II                





iFR Swedeheart

Over 4000 patients have been studied with iFR and numerous prospective iFR studies have been published in peer-reviewed journals.      



The two prospective, randomized, controlled trials, with more than 4500 patients' global 

physiology studies are Published in The New England Journal of Medicine.

iFR clinical progress

Clinical articles8,9

  1. Davies JE, et al., DEFINE-FLAIR: A Multi- Centre, Prospective, International, Randomized, Blinded Comparison of Clinical Outcomes and Cost Efficiencies of iFR and FFR Decision-Making for Physiological Guided Coronary Revascularization. N Engl J Med, epub March 18, 2017.
  2. Gotberg M, et al., Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve Guided Intervention (IFR-SWEDEHEART): A Multicenter, Prospective, Registry-Based Randomized Clinical Trial. N Engl J Med, epub March 18, 2017.
  3. Patel M. Cost-effectiveness of instantaneous wave-Free Ratio (iFR) compared with Fractional Flow Reserve (FFR) to guide coronary revascularization decision-making. Late-breaking Clinical Trial presentation at ACC on March 10, 2018.
  4. Escaned J. ADVISE II: A Prospective, Registry Evaluation of iFR vs. FFR. TCT 2013. Lecture conducted from San Francisco, CA.
  5. Sen S, et al. Development and validation of a new adenosine-independent index of stenosis severity from coronary wave-intensity analysis: results of the ADVISE (ADenosine Vasodilator Independent Stenosis Evaluation) study. J Am Coll Cardiol. 2012 Apr 10;59(15):1392-402.
  6. An iFR cut-point of 0.89 matches best with an FFR ischemic cut-point of 0.80 with a specificity of 87.8% and sensitivity of 73.0%. (From ADVISE II, and iFR Operator’s Manual 505-0101.23)
  7. Tonino et al. Fractional Flow Reserve Versus Angiography for Guiding Percutaneous Coronary Intervention. New England Journal of Medicine. 2009; 360, Number 3:213-224.
  8. Patel M, et al., ACC/AATS/AHA/ASE/ASNC/SCAI/SCCT/STS 2017 Appropriate Use Criteria for Coronary Revascularization in Patients with Stable Ischemic Heart Disease. J Am Coll Cardiol. 2017 May 2;69(17):2212-2241.
  9. ACC CathPCI Hospital Registry.
  10. Lofti A, et al. Focused update of expert consensus statement: Use of invasive assessments of coronary physiology and structure: A position statement of the society of cardiac angiography and interventions. Catheter Cardiovasc Interv. 2018;1–12.
  11. 2018 ESC/EACTS Guidelines on myocardial revascularization: The task force on myocardial revascularization of the European society of cardiology (ESC) and European association for cardio-thoracic surgery (EACTS). Eur Heart J. 2018;00:1-96.