instantaneous wave-free ratio
Pronunciation: EYE-eff-arr
Also written as: iFR — instantaneous wave-free ratio
A resting coronary physiology index that assesses functional significance of coronary stenosis without pharmacological vasodilation.
Full Definition
A diagnostic measurement (iFR) that evaluates the hemodynamic significance of coronary artery stenosis during the wave-free period of diastole when competing waves from reflected pressure and suction waves are naturally minimized. Unlike fractional flow reserve (FFR), iFR does not require administration of adenosine or other hyperemic agents, making the procedure faster and potentially more comfortable for patients. The measurement uses the ratio of distal coronary pressure to aortic pressure during this specific diastolic period, with values ≤0.89 considered hemodynamically significant. Clinical trials have demonstrated non-inferiority to FFR-guided revascularization strategies.
Usage
Usage note: Acronym iFR is widely accepted; capitalize when abbreviated, lowercase when spelled out.
In Context
- "The instantaneous wave-free ratio was measured in all intermediate lesions before randomization to medical therapy or PCI." — Methods section
- "Instantaneous wave-free ratio-guided revascularization was non-inferior to FFR-guided strategy for clinical outcomes." — Abstract conclusions