Background. Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are discordant in approximately 20% of cases, and it is unclear whether this is influenced by the physiological pattern of coronary artery disease (CAD). The pullback pressure gradient index (PPGi) can objectively characterize the physiological pattern of CAD and we therefore sought to evaluate whether this differed in discordant groups (FFR+/iFR- vs. FFR-/iFR+).
Methods: The study (NCT03857503) enrolled 355 patients (390 vessels) with chronic coronary syndrome who had at ≥1 epicardial coronary artery lesion with a 40%-90% diameter stenosis by visual assessment on invasive coronary angiography, and had analysable FFR, iFR, and PPGi derived from quantitative flow ratio (QFR). Cut-offs for hemodynamic significance were FFR≤0.80 and iFR≤0.89. Vessels were classified as FFR+/iFR+ (n=103;26.4%), FFR-/iFR+ (n=27;6.9%), FFR+/iFR- (n=38;9.7%), and FFR-/iFR- (n=222;57%) groups.
Results: Median FFR, iFR, and QFR were 0.84 (0.77-0.90), 0.92 (0.88-0.97), and 0.83 (0.73-0.90) respectively. FFR disagreed with iFR in 16.7% (65/390) of cases. The median PPGi was 0.75 (0.67-0.85). The physiological pattern of CAD was classified according to the PPGI as predominantly physiologically focal (PPGi ≥0.75) in 209/390 vessels (53.6%) or diffuse (PPGi <0.75) in 181/390 vessels (46.4%). The median PPGi was significantly lower in FFR- /iFR+ versus FFR+/iFR- vessels (0.65[0.60-0.69] vs 0.82[0.75-0.85], p<0.001). Predominantly physiologically focal disease was significantly associated with FFR+/iFR- (76.3% [29/38]), whilst predominantly physiologically diffuse disease was significantly associated with FFR-/iFR+ (96.3% [26/27]; p<0.001 for pattern of CAD between FFR+/iFR- and FFR-/iFR+ groups).
Conclusions: The physiological pattern of CAD is an important influencing factor in FFR/iFR discordance.
Editors
JACC: Cardiovascular Interventions Editor-in-Chief
David J. Moliterno, MD, FACC
JACC: Cardiovascular Interventions CME/MOC Editor
Michael C. McDaniel, MD
Author
Pruthvi C Revaiah, MD
Yoshinobu Onuma, MD, PhD
Patrick W. Serruys, MD, PhD
Important Dates
Date of Release: April 14, 2025
Term of Approval/Date of CME/MOC Expiration: April 13, 2026