FFR/iFR No Help in CABG Surgery in SWEDEHEART Registry

The use of fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR) to assess the functional significance of coronary lesions prior to CABG surgery is linked with a higher risk of early complications and does not improve clinical outcomes in short- or midterm follow-up, according to new observational data.

Anders Jeppsson, MD (University of Gothenburg, Sweden), who presented preliminary findings from the SWEDEHEART registry at the European Association for Cardio-Thoracic Surgery (EACTS) annual meeting in Milan, Italy, said “the results do not support that CABG generally should be based on the functional assessment of coronary stenoses.”

For PCI, the US revascularization guidelines recommend FFR or iFR in stable patients with angina, undocumented ischemia, and intermediate stenoses to help make a decision about PCI (class I, level of evidence A). The European Society of Cardiology and EACTS recommend FFR or iFR to assess the hemodynamic significance of an intermediate-grade stenosis when evidence of ischemia is not available (class I, level of evidence A). FFR-guided PCI should also be considered in patients with multivessel disease undergoing PCI (class IIa, level of evidence B).

In the surgical setting, however, there are limited data about the value of FFR or iFR, mostly because surgeons often aim for complete anatomic revascularization—usually those lesions with > 50% obstruction on angiography—rather than focusing only on those shown to be functionally significant. In an evidence review published in 2020, experts suggested that a functional assessment prior to CABG could reduce the number of distal anastomoses and simplify the surgery, but said there was no evidence FFR/iFR improves early clinical outcomes.

Higher Risk of Late Revascularization

The SWEDEHEART analysis included 17,735 patients who underwent isolated, first-time CABG between 2013 and 2020. Of these, 15.6% had a functional assessment of the stenoses prior to surgery (more than 80% with FFR) and the remainder underwent CABG without FFR/iFR guidance. The use of FFR/iFR increased over time, from 7% in 2013 to roughly 20% in 2020. Those who underwent functional testing were less likely to be women, were younger, had a lower risk for in-hospital mortality as assessed by EuroSCORE II, and received fewer peripheral anastomoses.

In multivariable-adjusted modeling, those assessed with FFR/iFR testing had a borderline higher risk of mortality at 30 days and a higher risk of the need for new dialysis. After a median follow-up of 3.6 years, there was no significant difference in mortality, postdischarge MI, stroke, new revascularization, or new coronary angiography between the two study arms.

In fact, investigators observed a late benefit in patients who underwent CABG alone, potentially suggesting that lesions left alone on the basis of FFR later went on to be problematic.

“For new revascularization, there was no difference in the first 3 years, but [the event curves] tended to diverge around 2 years,” said Jeppsson. “From the period between 3 to 7.5 years, there was a significantly higher risk for revascularization in the FFR/iFR-treated patients.”

In this landmark analysis, the late risk of new revascularization was 43% higher in patients who underwent functional testing versus those treated with CABG alone (P = 0.041). There was also a nonsignificant trend toward an increased need for angiography between 3 and 7.5 years (adjusted HR 1.13; P = 0.057).

Speaking during the late-breaking clinical trial session, Jeppsson acknowledged the study has limitations—namely, it’s observational and has a risk of selection bias and residual confounding. Still, said Jeppsson, it is a real-world study of a large number of patients included in validated databases and registries. Additionally, no patients were lost to follow-up, he said.