iFR, FFR confer similar safety at 5 years in real-world population
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Key takeaways:
- Strategies guided by instantaneous wave-free ratio and fractional flow reserve were equally safe for patients with heart disease at 5 years.
- The findings were reported in a real-world population.
SAN FRANCISCO — In a real-world population of patients with ACS or chronic coronary syndrome, a strategy guided by instantaneous wave-free ratio was similarly safe as one guided by fractional flow reserve at 5 years, data show.
The analysis of more than 42,000 patients from the National SWEDEHEART Quality Registry with coronary stenosis analyzed by instantaneous wave-free ratio (iFR; Philips) or FFR was presented at TCT 2023.
“One of the two randomized trials (DEFINE-FLAIR) showed an increase in long-term mortality with iFR, while iFR-SWEDEHEART was neutral,” Matthias Götberg, MD, PhD, interventional cardiologist and director of the cardiac catheterization lab at Skane University Hospital, Lund, Sweden, and associate professor of cardiology at Lund University, told Healio. “We wanted to evaluate whether this spurious signal was true or a play of chance — mortality was underpowered in DEFINE-FLAIR — using our national registries, which are unique since we can accurately track all patients indefinitely.”
The results of iFR-SWEDEHEART, published in March 2022 in the Journal of the American College of Cardiology, showed the strategies did not differ at 5 years in a randomized trial population in terms of MACE, death, MI or new revascularization, Götberg told Healio.
For the present study, in the nonrandomized, real-world SWEDEHEART registry population, the comorbidity burden was higher in the iFR group than in the FFR group, but after adjustment for known confounders, there was no difference between the groups in MACE at 5 years (iFR, 32.2%; FFR, 31.3%; adjusted HR = 0.99; 95% CI, 0.93-1.05; P = .72).
In addition, there were no 5-year differences in death (aHR = 1.04; 95% CI, 0.94-1.14; P = .43), MI (aHR = 0.94; 95% CI, 0.85-1.05; P = .3) or new revascularization (aHR = 1; 95% CI, 0.92-1.08; P = .98), and the results were consistent regardless of whether patients had revascularization performed immediately or deferred.
The results were not surprising because “FFR has never been shown to reduce mortality compared with angiography,” Götberg told Healio. “FFR is still valuable since it has been shown to accurately detect ischemia, increase precision of revascularization and reduce unnecessary PCI. iFR and FFR have about 85% agreement, and when comparing iFR and FFR with a third index as an arbiter, iFR is equally good or better at detecting ischemia. It would be surprising to find that iFR would cause an increase in mortality with that high degree of agreement. Also, in DEFINE-FLAIR, there was a similar outcome in terms of MI and new revascularization. It was odd that the difference in mortality didn't affect those two components of MACE. Thus, there were several indications that the increase in mortality was a play of chance. We felt, though, that it was important to investigate this in a larger dataset, since otherwise there would among certain cardiologists be a string of uncertainty regarding the safety of iFR.”
He said, as a result of these findings, “iFR should, in my mind, be the first choice due to better cost efficiency [and] no need to give a drug with associated side effects.”
References:
- Götberg M, et al. J Am Coll Cardiol. 2022;doi:10.1016/j.jacc.2021.12.030.
- Largest ever analysis (42,000 patients) of new real-world, long-term data demonstrates iFR and FFR are equally safe to diagnose and treat heart disease. Available at https://www.philips.com/a-w/about/news/archive/standard/news/press/2023/20231026-ifr-and-ffr-are-equally-safe-to-diagnose-and-treat-heart-disease-according-to-largest-ever-analysis-of-new-real-world-long-term-data.html. Published Oct. 25, 2023. Accessed Oct. 26, 2023.
Perspective
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About 5 years ago, we had two studies, iFR-SWEDEHEART and DEFINE-FLAIR, that showed equivalency of iFR to FFR. Because of considerations like time, money and patient discomfort with the need for adenosine in FFR, iFR was identified as equivalent after 1 year in both those trials. At 5 years, in iFR-SWEDEHEART, iFR remained just as good as FFR for guiding whether our patients with coronary disease should have PCI or other coronary intervention. However, DEFINE-FLAIR showed there was a mortality difference at 5 years in those that were treated by iFR vs. FFR, suggesting that maybe iFR is not as good as we thought for these patients. Since iFR-SWEDEHEART had not shown that at 5 years, the researchers looked at more real-world information on iFR vs. FFR from a national registry. There, iFR and FFR had similar results, suggesting that there is some unresolved difference in what was seen in the SWEDEHEART randomized trial and national registry compared to the DEFINE-FLAIR trial after 5 years. The researchers concluded that the mortality difference from DEFINE-FLAIR cannot be confirmed in this study. This suggests that a further corroborating study should be done to sort out the differences shown in mortality.
I think FFR will remain the gold standard for now. iFR may indeed be just as good at predicting risk as FFR, but there is still a concern about a mortality signal. And there were other signals earlier that iFR may not be as good as FFR for lesions in the left main artery and the proximal left anterior descending artery. There is more research to be done.
Collapse
Götberg M, et al. Late-Breaking clinical science session in structural heart disease: Session IV, in collaboration with the Journal of the American College of Cardiology. Presented at: TCT Scientific Symposium; Oct. 23-26, 2023; San Francisco (hybrid meeting).
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