Royal Philips has announced that the results from two large clinical trials comparing patient outcomes using instant wave-free ratio (iFR) and fractional flow reserve (FFR) in the diagnosis and treatment of heart disease have been published in the New England Journal of Medicine. First released in 2013, iFR is an innovative pressure-derived index unique to Philips, allowing hyperemia-free physiological assessment of coronary blockages. Findings from the DEFINE-FLAIR and iFR Swedeheart trials, which studied 4529 patients as part of the largest randomized coronary physiology outcome studies to date, were presented at the 2017 American College of Cardiology's Annual Scientific Session & Expo (ACC.17) in Washington, D.C., March 17–19, 2017.
In image-guided therapies of coronary artery disease, clinicians have been using FFR in addition to angiographic images to assess the physiology of a suspected blockage in coronary arteries to decide, guide, treat and confirm the appropriate therapy. iFR is the next-generation physiologic measurement that uses the same pressure guide wires and equipment as FFR, but avoids the administration of hyperemic agents to the patient that is required with FFR. The two trials demonstrate that, compared to FFR, iFR offers reduced procedure time, cost, and complexity without degradation of major adverse cardiac events (MACE). The primary endpoint of DEFINE-FLAIR and iFR Swedeheart was MACE rate at one year in iFR and FFR groups. DEFINE-FLAIR shows MACE rates of
6.8 percent in the iFR-guided arm versus 7.0 percent in the FFR-guided arm, p=0.003 for non-inferiority. The iFR Swedeheart outcome data showed MACE rates of
6.7 percent in the iFR-guided arm versus 6.1 percent in the FFR-guided arm, p=0.007 for non-inferiority.
The two trials further established that iFR offers a faster procedure while almost completely eliminating severe patient symptoms as compared to FFR. The DEFINE FLAIR study found that due to eliminating the need for a hyperemic drug, iFR-guided treatments lead to a
10 percent reduction in procedural time versus FFR-guided treatment (p=0.001), while reducing patient discomfort by 90 percent (p<0.01). Side effects of hyperemic drugs can include increased heart rate, pounding of the heart, flushing, elevated temperature and feelings of impending doom, which simulate physical and emotional distress.
Both studies conducted their comparisons of iFR versus FFR using pressure guide wires and equipment from Philips. Since the introduction of the hyperemia-free iFR modality in 2013, iFR has been studied in nearly 15,000 patients and is used in more than 4100 catheterization labs across the world.