Clinical studies demonstrate that physiologic lesion assessment to determine lesion significance and guide revascularization decisions is superior to angiographically guided treatment, and benefits patients with reduced rates of cardiac events [1,2]. Philips provides you the opportunity to use one of two clinically validated indices: iFR or FFR.
FFR and iFR can be obtained during routine coronary angiography by using a pressure wire to calculate the ratio between coronary pressure distal to a stenosis and the proximal aortic pressure. When resistance is constant, this ratio represents the potential decrease in coronary flow distal to the coronary stenosis.
The FFR modality uses hyperemic agents to achieve a state of constant resistance.
Pressure = flow x resistance
Fundamental equation for relating pressure flow derived from Poiseuille's Law for fluid dynamics
The iFR modality measures pressure during the wave-free period of the cardiac cycle when resistance is naturally constant.
Unlike FFR, iFR does not require administration of vasodilators because hyperemia is not necessary when measuring pressure during the wave-free period of the cardiac cycle.
iFR is a Class 1A recommendation and is proven to reduce procedure time, patient discomfort and cost compared to FFR [6,7].
The iFR modality provides a hyperemia-free measurement in as few as five heartbeats.
Both DEFINE FLAIR and iFR Swedeheart were designed with the dichotomous cut-point of iFR in the iFR arm[3,4]. With comparable MACE rates to FFR, these results mean the 0.89 cut-point for iFR is proven and backed by more than 4500 patients of outcome data.
FFR ischemia scale
An FFR lower than .80 is generally considered to be associated with myocardial ischemia.
iFR Coronary Physiology technology
Learn how you can guide PCI by using iFR index for measuring pressure in diagnostic & interventional procedures. See patient outcome data.