Why is this study important?

This is the first trial to provide long-term follow-up on the safety and efficacy of instantaneous wave-free ratio (iFR) compared with fractional flow reserve (FFR) to guide revascularization decisions. iFR-SWEDEHEART confirms after 5 years of follow-up that iFR is not inferior to FFR in guiding revascularization decisions in patients with stable coronary disease, unstable angina, or NSTEMI who had an indication for physiologically guided assessment. 

Should I change my practice because of these findings?

No. iFR has been widely adopted already based on multiple trials, including DEFINE-FLAIR, JUSTIFY-CFR, and the earlier outcomes from this registry-based randomized study.  iFR-SWEDEHEART provided reassuring 5-year follow-up data showing safety and efficacy of iFR were maintained on long-term follow-up, which is especially important since significantly more lesions appeared to be hemodynamically important in the FFR group than in the iFR group.

What question was this study supposed to answer?

Is iFR non-inferior to FFR in terms of clinical outcomes? Previous studies established that iFR is comparable to FFR when it comes to accurately detecting ischemia. iFR-SWEDEHEART was designed to study both the short-term and long-term clinical outcomes of iFR guided vs. FFR guided revascularization.

What did the study show?

There was no significant difference in the composite endpoint (all-cause death, myocardial infarction, or non-planned revascularization) at 5 years between iFR- and FFR-guided PCI.
 
The event rate was 21.5% with iFR and 19% with FFR, yielding a hazard ratio of 1.09 and non-inferiority P value = 0.007. Subgroup analyses of sex, age, comorbidities, smoking status, and angina symptoms showed no significant differences as well.

How good was the approach/methodology?

iFR-SWEDEHEART was a 2,037 patient registry-based randomized clinical trial. Lesions of 40-80% angiographic stenosis were randomized to iFR vs. FFR guided revascularization. The study was not blinded but had a well-designed non-inferiority analysis with well-balanced study groups. They reported 100% follow-up rate, which is very important when reporting long-term follow-up data.

All editors: Luai Tabaza, MD; Kirk N. Garratt, MD, MSc, MSCAI; and David A. Cox, MD, MSCAI