Significance of Intermediate Values of Fractional Flow Reserve in Patients with Coronary Artery Disease
Background—The fractional flow reserve (FFR) value of 0.75 has been validated against ischemic testing, while the FFR value of 0.80 has been widely accepted to guide clinical decision-making. However, revascularization when FFR is 0.76-0.80, within the so-called "gray zone", is still debatable.
Methods and Results—From February 1997 to June 2013, all patients with single-segment disease and an FFR value within the gray zone or within the two neighboring FFR strata (0.70-0.75 and 0.81-0.85) were included. Study endpoints consisted of major adverse cardiovascular events (MACE: death, myocardial infarction and any revascularization) up to 5 years. Out of 17380 FFR measurements, 1459 patients were included. Of them, 449 were treated with revascularization (Rev), and 1010 with medical therapy (MT). In the gray zone, MACE rate was similar (37[13.9%] vs. 21[11.2%], respectively, p=0.3) between MT and Rev, while a strong trend toward higher rate of death or myocardial infarction (25[9.4] vs. 9[4.8], p=0.06) and overall death (20[7.5] vs. 6[3.2], p=0.059) was observed in the MT group. Among MT patients, a significant step-up increase in MACE rate was observed across the 3 FFR strata, especially with proximal lesion location. In Rev patients, MACE rate was not different across the 3 FFR strata.
Conclusions—FFR in and around the "gray zone" bears a major prognostic value especially in proximal lesions. These data confirm that FFR ≤ 0.80 is valid to guide clinical decision-making.
- Received July 30, 2015.
- Revision received December 9, 2015.
- Accepted December 21, 2015.