Instantaneous Wave-Free Ratio versus Fractional Flow Reserve in Patients with Stable Angina Pectoris or Acute Coronary Syndromes - iFR-SWEDEHEART

Nov 04, 2021
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Author/Summarized by Author:
Anthony A. Bavry, MD, MPH, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
Philips Volcano
Date Presented:
11/04/2021
Date Published:
03/18/2017
Date Updated:
11/04/2021
Original Posted Date:
03/18/2017
References

Contribution To Literature:

Highlighted text has been updated as of November 4, 2021.

The iFR-SWEDEHEART trial showed that iFR was noninferior to FFR at preventing adverse cardiac events.

Description:

The goal of the trial was to evaluate if functional lesion assessment by instantaneous wave-free ratio (iFR) would be noninferior to FFR among patients with stable angina or acute coronary syndromes.

Study Design

  • Randomized
  • Parallel

Patients undergoing functional assessment of an indeterminant coronary lesion were randomized to iFR (n = 1,019) versus FFR (n = 1,018). Revascularization was recommended if the iFR value was ≤0.89 or the FFR value was ≤0.80.

  • Total number of enrollees: 2,037
  • Duration of follow-up: 12 months
  • Mean patient age: 67 years
  • Percentage female: 25%
  • Percentage with diabetes: 23%

Inclusion criteria:

  • Patients with stable angina or acute coronary syndrome (unstable angina or non-ST-segment elevation myocardial infarction [NSTEMI])
  • Indeterminant coronary stenosis 40-80% (non-culprit vessel in acute coronary syndrome patients)

Exclusion criteria:

  • Life expectancy <1 year
  • Killip class III or IV
  • Inability to tolerate adenosine
  • Previous coronary artery bypass grafting with patent graft to the interrogated vessel
  • Heavily calcified or tortuous vessel where inability to cross the lesion was expected

Other salient features/characteristics:

  • Radial access: 83%
  • Mean iFR: 0.91
  • Mean FFR: 0.82
  • Mean number of lesions evaluated: 1.55 with iFR vs. 1.43 with FFR (p = 0.002)
  • Functionally significant lesions: 29.2% with iFR vs. 36.8% with FFR (p < 0.0001)
  • Mean number of stents: 1.58 with iFR vs. 1.73 with FFR (p = 0.048)

Principal Findings:

The primary outcome, incidence of all-cause death, MI, or unplanned revascularization at 12 months, occurred in 6.7% of the iFR group versus 6.1% of the FFR group (p = 0.007 for noninferiority). The results were the same among tested subgroups.

Secondary outcomes:

  • Death: 1.5% for iFR vs. 1.2% for FFR
  • MI: 2.2% for iFR vs. 1.7% for FFR
  • Unplanned revascularization: 4.6% for iFR vs. 4.6% for FFR
  • Mild chest discomfort during the procedure: 2.6% with iFR vs. 31.4% with FFR

Long-term outcomes at 5 years:

  • Composite endpoint: hazard ratio (HR) 1.09 (95% confidence interval [CI] 0.90-1.33)
  • All-cause mortality: HR 1.20 (95% CI 0.89-1.62)
  • MI: HR 1.00 (95% CI 0.70-1.44)
  • Unplanned revascularization: HR 1.02 (95% CI 0.79-1.32)

Interpretation:

Among patients undergoing functional determination of an indeterminant coronary stenosis for stable or unstable coronary disease, iFR was noninferior to FFR. The threshold to revascularize was ≤0.89 for iFR and ≤0.80 for FFR. Adverse cardiac events were similar between study groups at 12 months and 5 years. There was less procedure-associated chest pain in the iFR group. Slightly more lesions were interrogated with iFR, possibly due to the simplicity of the procedure and lack of procedure-related chest pain, which can sometimes occur with adenosine. The preferential use of iFR over FFR for indeterminant lesions can be considered.

References:

Presented by Dr. Matthias Götberg at the Transcatheter Cardiovascular Therapeutics (TCT) Conference, Orlando, FL, November 4, 2021.

Götberg M, Christiansen EH, Gudmundsdottir IJ, et al., on behalf of the iFR-SWEDEHEART Investigators Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI. N Engl J Med 2017;376:1813-23.

Editorial: Bhatt DL. Assessment of Stable Coronary Lesions. N Engl J Med 2017;376:1879-81.

Presented by Dr. Matthias Götberg at the American College of Cardiology Annual Scientific Session (ACC 2017), Washington, DC, March 18, 2017.

Keywords: ACC17, ACC Annual Scientific Session, Acute Coronary Syndrome, Angina, Stable, Angioplasty, Coronary Angiography, Coronary Stenosis, Myocardial Infarction, Myocardial Revascularization, Outcome Assessment, Health Care, Registries, TCT21, Transcatheter Cardiovascular Therapeutics


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