Invasive physiology tests used in the ORBITA trial could not predict which patients would benefit from angioplasty more than placebo (sham procedure) in terms of the trial’s primary endpoint, improvement in exercise time. These data were presented at EuroPCR 2018 and published simultaneously in Circulation.
Results encourage debate over the importance of ischemia reduction with angioplasty using fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR), since these values were closely correlated with improvements on stress echocardiography. The lower the baseline FFR or iFR value, the greater the magnitude of benefit following angioplasty as compared with a placebo (sham procedure).
In an additional analysis (that was not pre-specified in the original protocol), more patients reported symptom improvement after “true” angioplasty than following a “placebo” procedure. However, neither FFR nor iFR modified this effect. Surprisingly, no relationship was seen between pre-randomization functional test results and changes in symptoms at 6 weeks.
Read also: SCAAR Registry at 10 years: FFR improves decision making in the long term.
Researchers expected intensity and frequency, along exercise time, to vary along the FFR spectrum, but this study showed (within certain technical limitations) that this correlation does not exist. Patients who have very highly ischemic FFR or iFR values did not gain much as regards symptoms after angioplasty, although they did benefit greatly regarding ischemia reduction on stress echo.
The overall results of the ORBITA trial were neutral, which limits the ability to do any secondary analyses such as this one.
FFR/iFR-guided angioplasty undoubtedly reduces ischemic burden. The problem is that the link between ischemia reduction and symptom relief is not as direct as we expected.
Original title: Fractional Flow Reserve and Instantaneous Wave-Free Ratio as Predictors of the Placebo-Controlled Response to Percutaneous Coronary Intervention in Stable Single-Vessel Coronary Artery Disease. Physiology-Stratified Analysis of ORBITA.
Reference: Al-Lamee R et al. EuroPCR 2018, simultaneously published in Circulation. 2018: Epub ahead of print.
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