instantaneous wave-free ratio
A resting index that assesses coronary stenosis significance without requiring adenosine-induced hyperemia.
Full Definition
Instantaneous wave-free ratio (iFR) is a relatively newer physiological index used to assess the functional significance of coronary artery stenosis without the need for pharmacological stress agents like adenosine. iFR is calculated during a specific period of diastole when competing influences are naturally minimized, providing a resting assessment of coronary flow limitation. Values ≤0.89 are considered abnormal and indicative of functionally significant disease. iFR offers advantages over traditional fractional flow reserve including patient comfort, procedural efficiency, and cost reduction while maintaining diagnostic accuracy.
Usage
Usage note: Commonly abbreviated as iFR; note the lowercase 'i' in the abbreviation.
In Context
- "Instantaneous wave-free ratio measurement provided functional assessment without adenosine administration." — Cardiac catheterization report
- "The instantaneous wave-free ratio of 0.85 confirmed hemodynamically significant stenosis." — Interventional cardiology procedure note