Age may impact results when making an angioplasty choice based on fractional flow reserve (FFR) vs. instantaneous wave-free ratio (iFR).

After 2 years of follow-up, patients whose treatment of intermediate lesions was deferred based on functional testing had similar outcomes regardless of whether this decision was informed by FFR or iFR. However, iFR performance was constant, while FFR performance varied according to age.

These results emerged from the assessment of two large, iconic randomized studies on this topic: DEFINE-FLAIR and iFR-SWEDEHEART.

A previous review of both trials had shown that iFR was noninferior to FFR in terms of the typical combined endpoint (death, infarction, unplanned revascularization), although iFR had led to the revascularization of less patients.

The higher divergence between methods was observed in younger patients, and such difference may have been driven by the vasodilator property of adenosine.

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While baseline flow is similar, the response to adenosine decreases with age. Consequently, the hyperemic flow is much higher in younger individuals.

The risk of events 2 years after randomization was equivalent for iFR and FFR in the analysis of all 4486 patients (10.45% vs. 9.71%; hazard ratio [HR]: 1.09; 95% confidence interval [CI]: 0.91-1.32) and also when specifically comparing deferred patients (7.43% vs. 7.40%; HR: 1.01; 95% CI: 0.74-1.38).

When comparing patients younger than 60, 42% were deferred with FFR and 54% with iFR (p < 0.01), with a 12% absolute difference in revascularization rate.

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Percentages were very similar (46% vs. 48%) for patients older than 60.

This information does not necessarily mean that iFR is better for younger patients; it just means that it is slightly more conservative when compared with FFR.

Original title: Two-year outcomes of patients with revascularization deferral based on FFR or iFR measurements: a pooled, patient level analysis of DEFINE FLAIR and iFR SWEDEHEART trials.

Reference: Escaned J. Presentado en forma virtual en el PCR virtual 2020.

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