Gray zone fractional flow reserve 0.81–0.85 is associated with an increased risk of cardio-vascular events

Aims Fractional Flow Reserve (FFR) is a widely accepted prognostic tool to estimate the risk of myocardial ischemia in coronary stenosis. Values above 0.80 are considered as an indication for medical therapy only. Whether intermediate values ranging from 0.81 to 0.85 are associated with an increase cardio-vascular (CV) risk is unknown. Methods In a prospective study, 91 patients with FFR > 0.80 were enrolled and followed up for at least 1 year. Clinical outcomes of the subgroup with FFR > 0.85 (N = 67) were compared with those of the subgroup with intermediate values of 0.81–0.85 (N = 24). The outcome was a composite of cardio-vascular death/myocardial infarction/CV hospitalization/target lesion revascularization. Results There was significant difference in baseline demographic data or medical therapy between the two groups ( Table 1 ). The average follow-up is 2.505 ± 0.6 years. We observed a significantly higher number of events in patients with FFR between 0.81 and 0.85 than in those with FFR > 0.85. These events occurred respectively in 45.9% and 13.4% of patients (P = 0.01) and were mostly the result of revascularizations and CV hospitalizations ( Fig. 1 ). Conclusion FFR values in the gray zone of 0.81–0.85 are correlated with an increased CV risk compared to FFR values > 0.85. Appropriately powered trials are needed to assess the potential benefit of revascularization in this subset of patients.