Instantaneous Wave-Free Ratio versus Fractional Flow Reserve guided intervention (iFR-SWEDEHEART): Rationale and design of a multicenter, prospective, registry-based randomized clinical trial

Am Heart J. 2015 Nov;170(5):945-50. doi: 10.1016/j.ahj.2015.07.031. Epub 2015 Aug 15.


Background: Instantaneous wave-free ratio (iFR) is a new hemodynamic resting index for assessment of coronary artery stenosis severity. iFR uses high frequency sampling to calculate a gradient across a coronary lesion during a period of diastole. The index has been tested against fractional flow reserve (FFR) and found to have an overall classification agreement of 80% to 85%. Whether the level of disagreement is clinically relevant is unknown. Clinical outcome data on iFR are scarce. This study is a registry-based randomized clinical trial, which is a novel strategy using health quality registries as on-line platforms for randomization, case record forms, and follow-up.

Design/methods: iFR-SWEDEHEART is a multicenter, prospective, randomized, controlled, clinical open-label clinical trial. Two thousand patients with stable angina or acute coronary syndrome and an indication for physiology-guided assessment of one or more coronary stenoses will be randomized 1:1 to either iFR- or FFR-guided intervention. The randomization will be conducted online in the Swedish web-based system for enhancement and development of evidence-based care in heart disease evaluated according to recommended therapies (SWEDEHEART) registry. The trial has a non-inferiority design, with a primary combined end point of all-cause death, non-fatal myocardial infarction, and unplanned revascularization at 12 months. End points will be identified through national registries and undergo central blind adjudication to ensure data quality.

Discussion: The iFR-SWEDEHEART trial is an registry-based randomized clinical trial evaluating the safety and efficacy of the diagnostic method iFR compared to FFR.

Trial registration: NCT02166736.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Acute Coronary Syndrome / diagnostic imaging
  • Acute Coronary Syndrome / physiopathology
  • Acute Coronary Syndrome / surgery*
  • Aged
  • Coronary Angiography
  • Female
  • Follow-Up Studies
  • Fractional Flow Reserve, Myocardial / physiology*
  • Humans
  • Male
  • Percutaneous Coronary Intervention / methods*
  • Prospective Studies
  • ROC Curve
  • Registries*
  • Severity of Illness Index
  • Treatment Outcome

Associated data