iFR

Full Definition

Instantaneous wave-free ratio (iFR) is a diagnostic index used to assess the hemodynamic significance of coronary stenoses. Unlike FFR, iFR does not require pharmacological vasodilation with adenosine, making the procedure faster and more comfortable for patients. The measurement is taken during a specific portion of diastole when microvascular resistance is naturally low and stable. iFR values ≤0.89 indicate hemodynamically significant stenosis requiring intervention, while values >0.89 suggest the lesion may be deferred.

Usage

Usage note: Always spell out on first use in clinical documentation.

In Context

• "The iFR measurement of 0.85 confirmed the need for PCI despite the angiographically moderate stenosis." — Catheterization laboratory report
• "Given the patient's contraindications to adenosine, iFR was chosen over FFR for physiological assessment." — Procedural planning note