Proven outcomes and superior value with iFR

  • By Philips
  • March 17 2025
  • 2 min read

iFR is the global gold standard among resting indices, with a Class IA recommendation in the ACC/AHA/SCAI and ESC Guidelines [1,3]. This is backed by clinical evidence and patient outcomes showing reduced costs, procedural time and patient discomfort [2]. iFR also provides advanced guidance with iFR pullback and co-registration for PCI planning throughout the entire case. Learn more about the latest iFR patient studies and view the latest 5-year outcomes update.

At-a-glance:

  • DEFINE PCI
  • Objective
  • Trial design
  • Results
  • DEFINE FLAIR and iFR Swedeheart
  • Consistent patient outcomes
  • Superior value
iFR Clinical evidence

DEFINE PCI

Unseen focal lesions cause residual ischemia. The DEFINE PCI study used iFR pullback to understand the rate and causes of residual ischemia in 500 patients undergoing contemporary PCI. Early results find that residual ischemia is common, and causes are treatable [2,5].

Objective

Understand residual ischemia as mapped by iFR pullback after successful angiographic PCI and its implications for procedural improvement.

Trial design

  • Primary endpoint: rate of residual ischemia (iFR<0.90) after angiographically successful PCI (residual diameter stenosis < 50% in any treated lesion)
  • Multi-center, prospective study in 22 US and six international centers
  • N=500 patients with CAD and iFR < 0.90 in at least one coronary artery with tandem, diffuse or multi-vessel intermediate lesions
  • Blinded iFR pullback to assess inschemia after PCI
  • One year patient follow-up

Results [6]

  • One in four patients with angiographically successful PCI left the cath lab with residual ischemia.
  • 68% relative reduction in clinical events at one year follow-up among patients achieving post-PCI iFR ≥ 0.95 (p-value=0.04)
  • Of the patients with residual ischemia, 81.6% were caused by an untreated angiographically inapparent physiologically focal stenosis (≤ 15 mm).
  • The final picture is often incomplete. iFR co-registration uncovers focal ischemia producing lesions missed visually.

DEFINE FLAIR and iFR Swedeheart

DEFINE Flair and iFR Swedeheart are two prospective randomized controlled studies published in the prestigious New England Journal of Medicine and combined represent the largest physiology clinical dataset with more than 4500 patients [7,9]. Learn more DEFINE FLAIR, iFR Swedeheart.

Proven Outcomes Graph 1

Consistent patient outcomes using iFR guided strategy, as with FFR

Image of Consistent patient outcomes using iFR guided strategy, as with FFR
Graph for Consistent patient outcomes using iFR guided strategy

* p-values are for non-inferiority of an iFR-guided strategy versus an FFR-guided strategy with respect to 1-year MACE rates; pre-specified non-inferiority margins were 3.4% and 3.2% in DEFINE FLAIR and iFR Swedeheart, respectively.

** MACE rates at 5-years: 21.5% iFR vs. 19.9% FFR (HR 1.09; 95% CI: 0.90, 1.33)

Superior value

Reduced costs per patient

DEFINE FLAIR and iFR Swedeheart found that on average, compared to FFR, iFR resulted in:

  • $896 dollars saved

Less procedural time

DEFINE FLAIR found that an iFR-guided strategy resulted in:

  • 10% reduction in procedural time
  • 40.5 minutes (iFR arm) vs. 45.0 minutes (FFR arm) [p<0.001]

Improved care

The two trials further established that an iFR-guided strategy enables a faster procedure while almost completely eliminating severe patient symptoms compared to an FFR-guided strategy.

  • DEFINE FLAIR reported a 90% reduction in patient discomfort.
  • iFR Swedeheart reported that with no hyperemic agent, you can achieve a 95.7% reduction in patient discomfort using an iFR-guided strategy.
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Footnotes
  1. Lawton J. et al. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization. JACC. 2022;79(2):e21-e129.
  2. Berntorp K, et al. Instantaneous wave-free ratio compared with fractional flow reserve in PCI: A cost-minimization analysis. Int J Cardiol 2021 1;344:54-59.
  3. 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. 20218;00:1-96.
  4. Nakamura M, et al. JCS/JSCVS 2018 Guideline on Revascularization of Stable Coronary Artery Disease. Circ J 2019; 83:1085–1196.
  5. Jeremias A et al. Blinded physiological assessment of residual ischemia after successful angiographic percutaneous coronary Intervention: The DEFINE PCI Study. JACC Cardiovasc Interv. 2019 Oct 28;12(20):1991-2001.
  6. Patel M., et al. 1-Year outcomes of blinded physiological assessment of residual ischemia after successful PCI. JACC Cardiol Interv. 2022;15(1):52-61.
  7. Davies JE, et al., Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI. N Engl J Med. 2017 24-1834.
  8. Götberg, Matthias et al. “5-Year Outcomes of PCI Guided by Measurement of Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve.” Journal of the American College of Cardiology vol. 79,10 (2022): 965-974. doi:10.1016/j.jacc.2021.12.030
  9. Götberg M, Christiansen EH, Gudmundsdottir IJ, Sandhall L, Danielewicz M, Jakobsen L, Olsson SE, Öhagen P, Olsson H, Omerovic E, Calais F, Lindroos P, Maeng M, Tödt T, Venetsanos D, James SK, Kåregren A, Nilsson M, Carlsson J, Hauer D, Jensen J, Karlsson AC, Panayi G, Erlinge D, Fröbert O; iFR-SWEDEHEART Investigators. Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI. N Engl J Med. 2017 May 11;376(19):1813-1823. doi: 10.1056/NEJMoa1616540. Epub 2017 Mar 18. PMID: 28317438.
Disclaimer
Results are specific to the institution where they were obtained and may not reflect the results achievable at other institutions. Results in other cases may vary.