instantaneous wave-free ratio
A pressure-derived index for assessing coronary stenosis significance without need for adenosine-induced hyperemia, abbreviated as iFR.
Full Definition
Instantaneous wave-free ratio (iFR) represents an adenosine-free method for physiological assessment of coronary stenosis severity, measuring the pressure ratio across a stenosis during the wave-free period of diastole when microvascular resistance is naturally minimized. Unlike fractional flow reserve, iFR does not require pharmacological vasodilation, making the procedure faster, more comfortable for patients, and potentially more cost-effective. The technology identifies a specific period during diastole when coronary flow is predominantly driven by pressure gradients rather than microvascular resistance. An iFR value ≤0.89 indicates hemodynamically significant stenosis warranting revascularization. This innovation has gained widespread adoption as an alternative to FFR for guiding percutaneous coronary intervention decisions.
Usage
Usage note: Lowercase except when abbreviated as iFR; hyphenate the full term.
In Context
- "Instantaneous wave-free ratio measured 0.85, indicating hemodynamically significant stenosis." — Physiological assessment report
- "The operator chose iFR over FFR to avoid adenosine administration in this patient." — Procedure decision rationale