Fractional Flow Reserve and Cardiac Events in Coronary Artery Disease: Data from a Prospective IRIS-FFR Registry (Interventional Cardiology Research Incooperation Society Fractional Flow Reserve)

Background: We evaluated the prognosis of deferred and revascularized coronary stenoses after fractional flow reserve (FFR) measurement to assess its revascularization threshold in clinical practice. Methods: The IRIS-FFR registry (Interventional Cardiology Research In-cooperation Society Fractional Flow Reserve) prospectively enrolled 5846 patients with ≥1coronary lesion with FFR measurement. Revascularization was deferred in 6468 lesions and performed in 2165 lesions after FFR assessment. The primary end point was major adverse cardiac events (cardiac death, myocardial infarction, and repeat revascularization) at a median follow-up of 1.9 years and analyzed on a per-lesion basis. A marginal Cox model accounted for correlated data in patients with multiple lesions, and a model to predict per-lesion outcomes was adjusted for confounding factors. Results: For deferred lesions, the risk of major adverse cardiac events demonstrated a significant, inverse relationship with FFR (adjusted hazard ratio, 1.06; 95% confidence interval, 1.05-1.08; P<0.001). However, this relationship was not observed in revascularized lesions (adjusted hazard ratio, 1.00; 95% confidence interval, 0.98-1.02; P=0.70). For lesions with FFR ≥0.76, the risk of major adverse cardiac events was not significantly different between deferred and revascularized lesions. Conversely, in lesions with FFR ≤0.75, the risk of major adverse cardiac events was significantly lower in revascularized lesions than in deferred lesions (for FFR 0.71-0.75, adjusted hazard ratio, 0.47; 95% confidence interval, 0.24-0.89; P=0.021; for FFR ≤0.70, adjusted hazard ratio 0.47; 95% confidence interval, 0.26-0.84; P=0.012). Conclusions: This large, prospective registry showed that the FFR value was linearly associated with the risk of cardiac events in deferred lesions. In addition, revascularization for coronary artery stenosis with a low FFR (≤0.75) was associated with better outcomes than the deferral, whereas for a stenosis with a high FFR (≥0.76), medical treatment would be a reasonable and safe treatment strategy. Clinical Trial Registration: URL: Http://www.clinicaltrials.gov. Unique identifier: NCT01366404.