Go Beyond the Angiogram

With a Comprehensive Physiology Assessment

FFR and RFR for Epicardial Assessment

To determine the need for percutaneous coronary intervention, physiology indices such as fractional flow reserve (FFR) and resting full-cycle ratio (RFR) are used to identify functionally significant epicardial coronary stenoses at stress or rest.1

Measure FFR and RFR with PressureWire™ X GuideWire, the world's only2,3 wireless physiology wire with a hydrophilic-coated3 design for exceptional handling performance and accurate measurements reliable readings.4,5

 PressureWire X GuideWire

Measuring FFR

FFR is a measure of blood pressure difference across a coronary artery stenosis to determine if a stenosis is physiologically significant, which can impede oxygen delivery to the heart muscle.1


Why Use FFR?


of the time angiography is inaccurate

Coronary angiography is not accurate in guiding the functional significance of stenosis in 34% of cases, compared to FFR.6


risk reduction in death/MI with FFR

 Two-year survival free of death/MI

FFR-guided percutaneous coronary intervention (PCI) leads to a 35% risk reduction in death and myocardial infarction (MI), compared to relying only on angiography.7


relative risk reduction in MACCE

 Month since randomisation

Complete revascularization with PressureWire™ X Guidewire led to a 62% relative risk reduction in major adverse cardiac and cerebrovascular events (MACCE) at 1 year.8 The DANAMI-3-PRIMULTI trial also revealed that untreated “FFR-positive” non-infarct-related artery lesions are associated with a 31% incidence of MACCE at 1 year.8

RFR — Resting Full-Cycle Ratio

Abbott's PressureWire™ X Guidewire measures resting full-cycle ratio (RFR), a resting index that can be measured as an alternative to FFR depending on the clinical situation.9 Like FFR, RFR can identify functionally significant epicardial coronary stenosis. Unlike FFR, RFR is a non-hyperemic index that does not require the administration of a vasodilator such as adenosine.9


Measuring RFR

Clinically equivalent to the instantaneous wave-free ratio (iFR) resting index, Abbott's RFR resting index scans through diastole and systole for the lowest pd/pa ratio. Unlike iFR or diastolic pressure ratio (dPR), RFR is calculated from the lowest value of Pd/Pa over the entire cardiac cycle.10

Measuring RFR Pressure Over Entire Cardiac Cycle

Advantage of RFR

"The major advantage of RFR over iFR is that RFR does not require identification of a specific landmark or selection of a specific time point during diastole. By calculating the minimum Pd/Pa over the entire cardiac cycle, RFR calculates the maximum pressure gradient across the stenosis during resting status."
– Lee, et al. Circulation 2019

The cutoff value of RFR is 0.89:9,11,12

  • When RFR ≤ 0.89, treatment with percutaneous coronary intervention (PCI) may be beneficial
  • When RFR > 0.89, deferral of PCI may be beneficial
 RFR Cutoff Value
Green indicates deferral may be beneficial and red indicates a treatment of PCI.

Assessing Serial or Diffuse Lesions with RFR Pullback

In patients with multiple sequential stenoses or diffuse lesions, pullback pressure assessment can identify lesions with functional significance. RFR can be calculated along the entire length of a stenotic vessel using pullback, which measures pressure gradient at any given location.9


 RFR Pullback

RFR Compared to Other Resting Indices

All resting pressure-derived indices closely correlate with one another, revealing the same discriminatory ability to guide intervention.10 The large IRIS-FFR retrospective study (1,506 patients, 1,833 lesions) examined deferred lesion failure among 5 resting indices—resting Pd/Pa, iFR, RFR, dPR, and DFR—and concluded that all resting indices had similar outcomes in deferred lesions.12

 Distribution of Physiologic Index

Here are the cutoff values for the various non-hyperemic pressure ratios.14

 Non-Hyperemic Pressure Ratios

Key RFR Findings

RFR has been studied in over 3,500 lesions and 2,500 patients, showing clinical accuracy and outcomes.

 RFR Results

Objective Decision Making: Drift Matters

Drift is a phenomenon that affects the accuracy of most pressure measurement devices.17 Accuracy is particularly critical for resting ratios, as clinical decisions from resting ratios are more impacted by drift than FFR.18,19


Compared to the hyperemic state, smaller separation between Pd and Pa at rest means even relatively small amounts of drift can lead to stenosis misclassification compared to FFR. That’s why it critical to detect even the slightest difference of pressure.

Use of FFR vs Non-Hyperemic Pressure Ratio (RFR)?14

Uses of FFR
 Non-Hyperemic IndexFFR
Left Main Coronary Artery20+++
Systolic Dysfuntion21+++
Post-PCI Side Branch Interrogation22+++
Post-PCI Assessment23+++
Equivalent Assessment
Multi-Vessel Disease24++++++
Uses of Non-Hyperemic Index (RFR)
Tandem Lesions26++++
Diffuse Lesions27++++
Left Anterior Descending28+++++
Acute Coronary Syndrome29+++++

Chart courtesy of Ziad Ali, MD.

Comprehensive Physiology Workflow

The PressureWire™ X Guidewire and CoroFlow Cardiovascular System can provide a comprehensive physiology assessment to measure FFR, RFR, IMR and CFR.


  1. Pijls, NH., et al. Measurement of fractional flow reserve to assess the functional severity of coronary-artery stenoses. N Engl J Med. 1996;334(26):1703-1708.
  2. Volcano Corp. Verrata guidewire and PrimeWire Prestige Plus guidewire IFUs, Opsens Inc. OptoWire guidewire and OptoWire II guidewire IFUs, ACIST Medical Systems. Navvus Microcatheter IFU, Boston Scientific Corporation. Comet guidewire IFU.
  3. PressureWire™ X Guidewire Instructions for Use (IFU). Refer to IFU for additional information.
  4. Pijls, NH., et al. Fractional Flow Reserve Versus Angiography for Guiding Percutaneous Coronary Intervention in Patients with Multivessel Coronary Artery Disease. 2-Year Follow-Up of the FAME Study. JACC. 2010; 56(3): 177-184.
  5. Fearon, WF., et al. Fractional Flow Reserve-Guided PCI as Compared with Coronary Bypass Surgery. N Engl J Med, Nov 4, 2021.
  6. Corcoran, D., et al. Fractional flow reserve: a clinical perspective. Int J Cardiovasc Imaging. 2017;33(7):961‐974.
  7. Pijls, NH., et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention in patients with multivessel coronary artery disease: 2-year follow-up of the FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) study. J Am Coll Cardiol. 2010;56(3):177‐184.
  8. Smits, PC., et al. Fractional flow reserve–guided multivessel angioplasty in myocardial infarction. N Engl J Med. 2017; 376:1234-1244.
  9. Svanerud, J., et al. Validation of a novel non-hyperaemic index of coronary artery stenosis severity: the Resting Full-cycle Ratio (VALIDATE RFR) study. EuroIntervention. 2018;14:806-814.
  10. Lee, JM., et al. Physiological and clinical assessment of resting physiological indexes. Circulation. 2019;139:889-900.
  11. Jeremias, A., et al. Resting full-cycle ratio (RFR): a novel physiologic index compared to Fractional Flow Reserve (FFR) in assessing the hemodynamic severity of a coronary stenosis: ILUMIEN I + PREDICT. EuroPCR 2018.
  12. Ahn, JM., et al. IRIS FFR: prognostic performance of five resting pressure-derived indexes of coronary physiology. TCT 2018.
  13. Nam, CW., et al. Fractional flow reserve assessment of serial lesions. Radcliffe Cardiology. April 2014.
  14. Ali, Z., Invasive Assessment of Coronary Physiology Is Here to Stay! TCT 2019.
  15. Kumar, G., et al. RE-VALIDATE: REal world VALIDATion of the non-hyperemic InDex of coronary Artery sTEnosis severity: resting full-cycle ratio (RFR) – RE-VALIDATE RFR. CRT 2019.
  16. Lee, JM., et al. Clinical Outcome of Lesions with discordant results among different invasive physiologic indices. Circulation Journal 2019 83:2210-2221.
  17. Jeremias, A., et al. A Test in Context: FFR: Accuracy, Prognostic Implications, and Limitations. J AM Coll Cardiol. 2017; 69:2748-58.
  18. Veer, M, et al. Comparison of Different Diastolic Resting Indexes to iFR. J AM Coll Cardiol. 2017;70(25):3088-3096.
  19. Cook, C. Quantification of the Effect of Pressure Wire Drift on the Diagnostic Performance of FFR, iFR, & Pd/Pa. Circ Cardiovasc Interv. 2016;9(4):e002988.
  20. Mallidi, J., et al. Long-term outcomes following fractional flow reserve-guided treatment of angiographically ambiguous left main coronary artery disease: a meta-analysis of prospective cohort studies. Catheter Cardiovasc Interv. 2015;86(1):12-18.
  21. Johnson, NP., et al. Diastolic pressure ratio: new approach and validation vs the instantaneous wave-free ratio. Eur Heart J. 2019; 40(31):2585-2594
  22. Koo, BK., et al. Physiologic assessment of jailed side branch lesions using fractional flow reserve. J Am Coll Cardiol. 2005;46(4):633-637.
  23. Johnson, NP., et al. Prognostic value of fractional flow reserve: linking physiologic severity to clinical outcomes. J Am Coll Cardiol. 2014;64(16):1641-1654.
  24. Escaned, J., et al. Clinical outcomes of state-of-the-art percutaneous coronary revascularization in patients with de novo three vessel disease: 1-year results of the SYNTAX II study. Eur Heart J. 2017;38(42):3124-3134.
  25. DEFINE-FLAIR Trial Investigators. Comparison of major adverse cardiac events between instantaneous wave-free ratio and fractional flow reserve–guided strategy in patients with or without type 2 diabetes. JAMA Cardiol. 2019;4(9):857-864.
  26. Nijjer, SS., et al. Pre-angioplasty instantaneous wave-free ratio pullback provides virtual intervention and predicts hemodynamic outcome for serial lesions and diffuse coronary artery disease. JACC Cardiovasc Interv. 2014;7(12):1386-96.
  27. Jeremias, A., et al. Blinded physiological assessment of residual ischemia after successful angiographic percutaneous coronary intervention: the DEFINE PCI study. JACC Cardiovasc Interv. 2019;12(20):1991-2001.
  28. Sen, S., et al. Clinical eventsa after deferral of LAD revascularization following physiological coronary assessment. J Am Coll Cardiol. 2019;73(4):444-453.
  29. Escaned, J., et al. Safety of the deferral of coronary revascularization on the basis of instantaneous wave-free ratio and fractional flow reserve measurements in stable coronary artery disease and acute coronary syndromes. JACC Cardiovasc Interv. 2018;11(15):1437-1449.

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