Coronary physiology-guided percutaneous coronary intervention — using fractional flow reserve or instantaneous wave-free ratio to assess the hemodynamic significance of coronary lesions before stenting — has transformed cath lab practice, with the Cath Lab Market reflecting the commercial adoption of pressure wire technology and non-invasive physiological assessment software that has improved clinical outcomes by avoiding stenting of hemodynamically insignificant lesions.

The landmark DEFER, FAME, and FAME-2 trials established that FFR-guided PCI — deferring revascularization for lesions with FFR above 0.80 — reduces unnecessary stent implantation, procedural complications, and major adverse cardiac events compared to angiography-guided stenting of visually intermediate lesions that FFR assessment reveals as hemodynamically non-significant. FAME-2's demonstration that FFR-guided PCI reduces urgent revascularization compared to medical therapy for hemodynamically significant lesions confirmed both the value of physiological assessment and the benefit of revascularizing truly significant disease.

iFR — instantaneous wave-free ratio measured during the diastolic pressure-free period without adenosine — provides equivalent physiological assessment to adenosine-dependent FFR in the DEFINE-FLAIR and iFR-SWEDEHEART trials while eliminating the adenosine infusion requirement that adds cost, time, and patient discomfort. iFR adoption in clinical practice has been facilitated by the equivalent diagnostic performance without adenosine administration.

Quantitative flow ratio — non-invasive physiological assessment computed from 3D coronary reconstruction of angiographic images without pressure wire — represents the emerging technology enabling physiological assessment of every coronary stenosis from standard angiographic acquisitions, potentially making physiological guidance universally accessible without additional catheter-based measurements.

Do you think AI-computed angiography-based physiology will eventually replace pressure wire-based FFR as the standard physiological assessment in cath labs?

FAQ

What is FFR in cardiac catheterization? Fractional flow reserve is the ratio of maximal coronary blood flow across a stenosis to the theoretical normal flow, measured using a pressure wire with adenosine-induced maximal hyperemia; FFR below 0.80 indicates hemodynamically significant stenosis warranting revascularization.

What is iFR and how does it differ from FFR? iFR measures coronary pressure ratio during the diastolic wave-free period without requiring adenosine administration, providing equivalent physiological stenosis assessment to FFR with greater patient comfort and simplified procedure workflow.

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