instantaneous wave-free ratio
Pronunciation: EYE-eff-ar
Resting pressure-derived index for assessing functional significance of coronary stenoses without pharmacological hyperemia.
Full Definition
Instantaneous wave-free ratio (iFR) is a relatively new method for evaluating the hemodynamic significance of coronary stenoses that does not require pharmacological vasodilation. The measurement is taken during the wave-free period of diastole when resistance is naturally at its minimum and flow is maximal. iFR provides similar diagnostic accuracy to FFR for identifying ischemia-causing lesions, with values ≤0.89 considered abnormal. This technique offers advantages in terms of patient comfort, procedural time, and cost while maintaining comparable clinical outcomes to FFR-guided intervention strategies.
Usage
Usage note: Increasingly used as an alternative to FFR due to elimination of hyperemic agents.
In Context
- "The instantaneous wave-free ratio was 0.85, suggesting the lesion was not hemodynamically significant." — Cardiac catheterization report
- "iFR-guided treatment showed non-inferiority to FFR-guided intervention in the clinical trial." — Research publication