instantaneous wave-free ratio
Also written as: iFR — instantaneous wave-free ratio
A physiological index for assessing coronary stenosis severity without the need for hyperemic agents.
Full Definition
Instantaneous wave-free ratio (iFR) is a resting physiological measurement that assesses the functional significance of coronary stenosis during the wave-free period of diastole when microvascular resistance is naturally at its lowest. Unlike fractional flow reserve, iFR does not require administration of adenosine or other hyperemic agents, making the procedure faster and more comfortable for patients. An iFR value of 0.89 or less indicates hemodynamically significant stenosis. Clinical trials have demonstrated non-inferiority of iFR-guided revascularization compared to FFR-guided strategies.
Usage
Usage note: Lowercase 'i' in iFR is standard; do not capitalize unless beginning sentence.
In Context
- "Instantaneous wave-free ratio measurement eliminated the need for adenosine administration during the diagnostic catheterization." — Procedural report
- "The instantaneous wave-free ratio of 0.85 confirmed the hemodynamic significance of the left circumflex lesion." — Catheterization laboratory report