ACC 2018 | DEFINE-FLAIR Sub-Analysis: iFR More Comfortable, Faster, and Much Cheaper

Using instantaneous wave-free ratio (iFR) to guide decisions on revascularization of intermediate lesions is cheaper than using fractional flow reserve (FFR). Based on costs from the DEFINE-FLAIR trial, researchers estimate the difference to be almost USD 1000.

This should not be seen as good news for any given technology (iFR, in this case), but for physiologic assessment as a general concept. Many more interventional cardiologists need to start using physiologic assessment as a standard course of action in their cath labs, because there is much evidence that it improves outcomes.


FFR requires maximum hyperemia, which is achieved by using adenosine—with its associated side effects and costs. On the other hand, iFR calculates the pressure gradient of a lesion during diastole, immediately after the dicrotic wave, when physiologic resistance is minimum. That renders unnecessary the use of hyperemic agents.

Read also: NOTION: 5-Year Outcomes of TAVR vs. Surgery in Low-Risk Patients are Promising.

Last year, DEFINE-FLAIR and iFR-SWEDEHEART results proved the noninferiority of iFR in terms of events compared with FFR measurement.


The difference in terms of costs is driven by the fact that FFR-guided procedures identified more significant lesions that required treatment. More time must go by for the assessment of this aspect. If, in the future, some lesions left untreated with iFR require reintervention, the equation might be inverted by the late catch-up phenomenon. The opposite might also turn out to be true: less stenting with iFR might derive in less restenosis and less future thrombosis.


Original title: Comparative Cost-Effectiveness of the Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Coronary Revascularization Decision-Making.

Presenter: Patel MR.

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