Fractional Flow Reserve in the Grey Zone and Benefit of PCI

Study Questions:

What is the clinical utility of revascularization performed for fractional flow reserve (FFR) in the grey zone (0.75-0.80)?


The author studied the outcome of 1,334 native coronary stenosis with grey-zone FFR values in 1,334 patients who were enrolled in the prospective multicenter IRIS-FFR (Interventional Cardiology Research In-cooperation Society Fractional Flow Reserve) registry. Revascularization was deferred for 683 patients (deferred group) and performed for 651 (performed group). The primary outcome was the composite of death, target vessel myocardial infarction (MI), and target vessel revascularization (TVR).


The median follow-up was 2.9 years. There was no difference in the primary endpoint (8.1% in the deferred group vs. 8.4% in the performed group; adjusted hazard ratio [aHR], 1.05; 95% confidence interval [CI], 0.67-1.66; p = 0.79). There was no difference in the incidence of mortality (2.5% vs. 2.0%; aHR, 0.82; 95% CI, 0.34-2.00; p = 0.66) or spontaneous MI (0.7% vs. 0.5%; aHR, 1.85; 95% CI, 0.35-9.75; p = 0.47). Overall MI rate was significantly higher in the performed group (0.7% vs. 3.2%; aHR, 0.27; 95% CI, 0.09-0.80; p = 0.02) because of a higher risk of periprocedural MI. TVR was significantly higher in the deferred group (5.7% vs. 3.7%; aHR, 2.17; 95% CI, 1.17-4.02; p = 0.01).


For coronary stenosis with grey-zone FFR, revascularization was not associated with better clinical outcomes compared to a deferred revascularization approach.


The optimal FFR cut off for revascularization has been the subject of some controversy. In the FAME 2 study, revascularization for coronary stenosis was associated with improved clinical outcomes in lesions with an FFR ≤0.80, whereas in many other studies, medical therapy was associated with favorable outcomes with an FFR ≥0.75. This study found no difference in the outcome of patients with deferred versus immediate revascularization in lesions with an FFR in the grey zone. Since the absolute difference in TVR was low, and there was no difference in hard endpoints, and absent randomized data to the contrary, deferred revascularization should be the preferred approach for lesions with an FFR in the grey zone.

Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Atherosclerotic Disease (CAD/PAD), Aortic Surgery, Interventions and ACS, Interventions and Coronary Artery Disease

Keywords: Acute Coronary Syndrome, Coronary Artery Disease, Coronary Stenosis, Fractional Flow Reserve, Myocardial, Myocardial Infarction, Myocardial Revascularization, Percutaneous Coronary Intervention, Treatment Outcome

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