Optimal Treatment Strategy for Coronary Artery Stenoses with Grey Zone Fractional Flow Reserve Values. A Systematic Review and Meta-Analysis.

Objectives: We conducted a review and meta-analysis of published data to compare revascularization to deferral strategy for coronary lesions with grey zone fractional flow reserve (FFR).

Background: Optimal treatment for coronary stenoses with FFR values between 0.75 and 0.80, the so-called grey zone, remains a matter of debate.

Methods: We included all studies evaluating revascularization versus deferral for lesions with grey zone FFR. The primary outcome was study-defined major adverse cardiac events (MACE). Secondary outcomes were the composite of death or MI and target vessel revascularization (TVR). A total of 2362 patients were included, of whom 1181 underwent revascularization (revascularization group) and 1181 received medical treatment only (deferral group).

Results: After a mean follow-up period of 2.4 years, no difference was found for the primary outcome of the study-defined MACE between the two groups [RR = 1.33 (0.73-2.44), p = 0.35]. In addition, there was no difference for the secondary outcomes of death or MI and TVR between the two groups [RR = 1.39 (0.56-3.47), p = 0.48 and RR = 1.49 (0.89-2.51), p = 0.13, respectively].

Conclusions: In this meta-analysis revascularization of coronary stenoses with grey zone FFR showed no advantage over a deferral strategy in terms of study-defined MACE. Case by case judgment should be implemented to guide treatment in this special subset of patients.