iFR, FFR associated with similar outcomes in deferred revascularization

According to a pooled patient-level analysis, instantaneous wave-free ratio was associated with similar 1-year clinical outcomes compared with fractional flow reserve in patients with deferred revascularization.

However, among patients with ACS whose revascularization was deferred, those whose decision was guided by FFR had a higher rate of MACE than those whose decision was guided by instantaneous wave-free ratio (iFR), researchers found.

In the DEFINE-FLAIR and iFR-SWEDEHEART trials, 1-year rates of MACE were similar between those who underwent revascularization guided by iFR and those who underwent revascularization guided by FFR. For the present study, presented by Javier Escaned, MD, PhD, FESC, head of the interventional cardiology section and associate professor of medicine, department of cardiology, Hospital Clínico San Carlos, Madrid, at EuroPCR, researchers analyzed 1-year outcomes of patients from DEFINE-FLAIR and iFR-SWEDEHEART, including whether the outcomes differed by iFR/FFR assignment and whether they differed in patients with ACS vs. patients with stable CAD.

There were 2,130 patients whose revascularization was deferred based on iFR or FFR results (mean age, 66 years; 70% men), and 2,350 who were treated immediately (mean age, 66 years; 80% men). The treated group had higher rates of male sex (P < .01), diabetes (P < .01) and prior PCI (P = .03).

The purpose was “to expand the power that we already had from DEFINE-FLAIR and iFR-SWEDEHEART, which together expand the information we have in the field of coronary physiology by fourfold. By bringing them together, it’s enabled us to answer even more questions … and potentially to be even more helpful for the cardiology community,” Justin Davies, MBBS, PhD, consultant cardiologist at Imperial College London and principal investigator of DEFINE-FLAIR, told Cardiology Today’s Intervention.

Justin Davies

Among those deferred, 1.9% were post-STEMI, 18.7% had non-ST-segment elevation ACS and 78.6% had stable CAD, and the breakdown was similar between the iFR and FFR groups.

Fifty percent of those assigned iFR in the original trials had revascularization deferred compared with 45% of those assigned FFR.

Among those deferred, 4.12% of the iFR group and 4.05% of the FFR group had MACE at 1 year (HR = 1.05; 95% CI, 0.69-1.6), according to the researchers. Results were consistent regardless of sex, diabetes status, hypertension status, prior MI and prior PCI.

“One of the most important things we found is the improvement in the safety of deferral over the last 20 years,” Davies said. “In the DEFER study, there was an event rate of about 8% [in patients with deferred revascularization], and … now we know the event rate is about half of that. The safety of deferral is very good in modern cath lab and pharmacological treatments. It’s reassuring for anyone using physiology to guide coronary revascularization.”

In the deferred cohort, rates of 1-year MACE were 5.9% in those with ACS and 3.6% in those with stable CAD (HR = 0.62; 95% CI, 0.39-0.99), whereas in the treated cohort, rates of 1-year MACE were 8.7% in those with ACS and 8.5% in those with stable CAD (HR = 0.91; 95% CI, 0.67-1.24), the researchers found.

Among those whose revascularization was deferred due to FFR results, 6.4% of those with ACS had MACE at 1 year vs. 3.4% of those with stable CAD (HR = 0.52; 95% CI, 0.27-1), and among those whose revascularization was deferred due to iFR results, 5.4% of those with ACS had MACE at 1 year vs. 3.8% of those with stable CAD (HR = 0.74; 95% CI, 0.38-1.43), according to the researchers.

“If we defer patients with ACS, they do worse than patients with stable [CAD],” Davies said. “Until the release of these studies, we weren’t sure if that was to do with the fact that they’re ACS patients, or if it had something to do with FFR. … We know when people have disease in their coronary arteries, they often have disruptive plaques among their circulation, and then the effect of the adenosine is less powerful. What that really means is you can have an underestimation of lesion severity [and] can defer lesions inappropriately and have an increase in MACE. The only way to show that is to compare it with another technique, in this case iFR, which uses no adenosine at all.

“[These results] mean we were probably inappropriately deferring a few patients with ACS when using FFR,” he said. “In the ACS group, the deferral rates were the same between iFR and FFR, so the answer to the question of whether it is the iFR deferring fewer patients or the FFR deferring more is the latter. As a result, we see worse MACE probably because you’re not able to induce as much hyperemia in these patients. And now there is an alternative which doesn’t suffer from the same problem.”

The data produced by DEFINE-FLAIR and iFR-SWEDEHEART are “very likely to change guidelines,” Davies told Cardiology Today’s Intervention. – by Erik Swain

Reference:

Escaned J, et al. Late-breaking trials and trial updates – Session comprising selected late-breaking trial submissions. Presented at: EuroPCR; May 16-19, 2017; Paris.

Disclosure: DEFINE-FLAIR and iFR-SWEDEHEART were funded through unrestricted grants from Philips Volcano. Davies reports financial ties with Medtronic and Volcano Corp. and being an inventor of the iFR technique. Escaned reports speaking for Abbott, AstraZeneca, Biosensors, Boston Scientific, Medtronic, OrbusNeich and Philips Healthcare.