Functional Diagnostic Accuracy of Quantitative Flow Ratio in Online Assessment of Coronary Stenosis III Europe - FAVOR III Europe

Oct 30, 2024
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Author/Summarized by Author:
Amit Saha, MD
Summary Reviewer:
Dharam J. Kumbhani, MD, SM, FACC
Trial Sponsor:
Medis Medical Imaging Systems and Aarhus University Hospital Skejby
Date Presented:
10/30/2024
Date Published:
10/30/2024
Original Posted Date:
10/30/2024
References

Contribution To Literature:

The FAVOR III Europe trial showed that in patients with chronic or acute coronary syndrome, noninvasive functional testing of intermediate stenoses with quantitative flow ratio (QFR) resulted in more frequent MACE compared with FFR-guided revascularization.

Description:

The goal of the trial was to test the noninferiority of noninvasive, angiography-based quantitative flow ratio (QFR) compared with fractional flow reserve (FFR) in the functional assessment of coronary stenoses of intermediate severity.

Study Design

  • Multicenter
  • Open-label
  • Randomized

Patients with coronary artery disease and ≥1 lesion with intermediate stenosis were randomized in 1:1 fashion to functional testing with QFR (Medis Suite QAngio XA-3D QFR system, n = 1,008) or FFR (n = 992) to guide revascularization decision-making. Complete revascularization (simultaneous or staged) was mandated with a cutoff of ≤0.80 for both QFR and FFR.

  • Total number screened: 2,369
  • Total number of enrollees: 2,000
  • Duration of follow-up: 12 months
  • Mean patient age: 66 years
  • Percentage female: 23%

Inclusion criteria:

  • Age ≥18 years
  • Chronic (CCS) or stabilized acute coronary syndrome (ACS): stable angina, acute non–ST-segment elevation myocardial infarction (NSTEMI), or staged evaluation of nonculprit lesion following NSTEMI or STEMI >24 hours prior
  • Intermediate coronary artery stenosis (40-90%) in ≥2.5-mm diameter vessel

Exclusion criteria:

  • STEMI ≤24 hours prior
  • Cardiogenic shock
  • Estimated glomerular filtration rate <20 mL/min/1.73 m2
  • Left ventricular ejection fraction <30%
  • Left main or ostial right coronary artery (RCA) >50% stenosis
  • Chronic total occlusion of any vessel
  • Bypass graft to target vessel

Other salient features/characteristics:

  • CCS: 65%
  • Diabetes: 25%
  • Prior percutaneous coronary intervention: 49%
  • Left anterior descending (LAD) target vessel: 66%
  • Multivessel coronary disease: 44%
  • Clinical indication CCS: 67%
  • Number of diseased vessels ≥1: 45%

Principal Findings:

The primary outcome, major adverse cardiovascular event (MACE), a composite of all-cause death, MI, and unplanned revascularization, for QFR vs. FFR at 12 months, was: 6.7% vs. 4.2%, hazard ratio (HR) 1.63 (95% confidence interval [CI] 1.11-2.41), 2-sided p = 0.013

  • Event proportion difference 2.5% (90% CI 0.9-4.2), exceeding noninferiority margin of 3.4%

Secondary outcomes for QFR vs. FFR at 12 months:

  • All-cause death: 1.4% vs. 1.1%, HR 1.25 (95% CI 0.57-2.56), p = 0.58
  • MI: 3.7% vs. 2.0%, HR 1.84 (95% CI 1.07-3.17), p = 0.028
  • Unplanned revascularization: 3.3% vs. 2.5%, HR 1.36 (95% CI 0.81-2.30), p = 0.25
  • Target vessel failure (composite of cardiac death and target-vessel MI or revascularization): 5.0% vs. 3.6%, HR 1.42 (95% CI 0.92-2.19), p = 0.11

Procedural characteristics for QFR vs. FFR:

  • Median QFR/FFR: 0.81 vs. 0.84
  • Any study lesion revascularization: 54.4% vs. 45.8%
  • Proportion of functionally significant lesions in left circumflex (LCx) system: 37.2% vs. 15.4%
  • Total number of stents implanted in study lesions: 823 vs. 650
  • Total procedure time: 46 vs. 46 minutes
  • Contrast volume: 140 vs. 140 mL

Interpretation:

FAVOR III China demonstrated decreased 1-year MACE with QFR versus angiography-guided revascularization, leading to a class IB recommendation for QFR in the management of intermediate stenoses in CCS in the 2024 European guidelines. However, QFR failed to meet the prespecified noninferiority margin in the current study (FAVOR III Europe), largely due to an increase in MI, compared with FFR in a mixed cohort of ACS and CCS. This novel finding was observed despite multiple studies demonstrating excellent concordance between QFR and FFR/instantaneous wave-free ratio (iFR) measurements and in nonrandomized outcomes comparisons of QFR and FFR/iFR. LCx and obtuse marginal lesions were uniquely over twice as likely to be functionally significant by QFR, which has not been previously described.

Further study is needed to identify whether outcomes with QFR may differ by target vessel or in tandem versus single lesions. QFR may still be preferable to angiography-only assessment based on FAVOR III China, especially in patients with markedly positive abnormal QFR testing. However, coupled with the more frequent revascularization observed with QFR, the observed increase in MACE does not support QFR assessment of intermediate lesions when FFR/iFR is available.

References:

Andersen BK, Sejr-Hansen M, Maillard L, et al. Quantitative flow ratio versus fractional flow reserve for coronary revascularization guidance (FAVOR III Europe): a multicenter, randomized, non-inferiority trial. Lancet 2024;Oct 30:[Epub ahead of print].

Presented by Dr. Birgitte Krogsgaard Andersen at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2024), Washington, DC, October 30, 2024.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Aortic Surgery, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Coronary Angiography, Coronary Stenosis, Fractional Flow Reserve, Myocardial, Myocardial Revascularization, Percutaneous Coronary Intervention, TCT24, Transcatheter Cardiovascular Therapeutics


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