Combined pressure and flow measurements to guide treatment of coronary stenoses

Objectives: The aim of this study was to assess clinical outcomes after
combined pressure and flow assessment of coronary lesions. Background:
Although fractional flow reserve (FFR) remains the invasive reference
standard for revascularization, approximately 40% of stenoses have
discordant coronary flow reserve (CFR). Optimal treatment for these
disagreements remains unclear. Methods: A total of 455 subjects with 668
lesions were enrolled from 12 sites in 6 countries. Only lesions with
reduced FFR and CFR underwent revascularization; all other combinations
received initial medical therapy. Results: Fourteen percent of lesions had
FFR<=0.8 but CFR>=2.0 while 23% of lesions had
FFR>0.8 but CFR<2.0. During 2-year follow-up, the primary
endpoint of composite all-cause death, myocardial infarction, and
revascularization in lesions with FFR<=0.8 but CFR>=2 (10.8%
event rate) compared with lesions with FFR>0.8 and CFR>=2
(6.2% event rate) exceeded the prespecified +10% noninferiority margin (P
= 0.090). Target vessel failure models using both continuous FFR and
continuous CFR found that only higher FFR was associated with reduced
target vessel failure (Cox P = 0.007) after initial medical treatment.
Central core laboratory review accepted 69.8% of all tracings with mean
differences of <0.01 for FFR and <0.02 for CFR, indicating
no material impact on clinical measurements or outcomes. Conclusions:
All-cause death, myocardial infarction, and revascularization after 2
years was not noninferior between lesions with FFR<=0.8 but
CFR>=2 and lesions with FFR>0.8 and CFR>=2. These
results do not support using invasive CFR>=2 to defer
revascularization for lesions with reduced FFR if the patient would
otherwise be a candidate on the basis of the entire clinical scenario and
treatment preference.