Seven-year clinical outcomes of patients with moderate coronary artery stenosis after deferral of revascularization based on gray-zone fractional flow reserve

The range (0.75–0.80) of fractional flow reserve (FFR) is known as the gray zone. Although the FFR of 0.80 was recently adopted as the cutoff value for coronary revascularization, the long-term clinical outcomes of patients with angiographically moderate coronary artery stenosis (FFR: 0.75–0.80) remain unknown. The objective of the present study was to investigate the clinical outcomes of patients with angiographically moderate coronary artery stenosis, whose FFR was 0.75–0.80. One hundred and twenty consecutive patients, for whom coronary revascularization was deferred based on FFR, were categorized to groups I and II, in which 55 and 65 patients had FFRs of 0.75–0.80 and 0.81–0.85, respectively. Adverse cardiac events included all-cause death, cardiac death, myocardial infarction, coronary revascularization for the FFR-measured and -unmeasured arteries, congestive heart failure, and admission for chest symptoms. Patients were followed up for 7 years after coronary angiography. Event-free survival rates of all adverse cardiac events were 73 % in group I and 63 % in group II (P = 0.35) and those of adverse cardiac events related to the FFR-measured artery were 94 and 85 % (P = 0.08). Throughout the follow-up period, the medication rate of statins was significantly lower in group II than in group I (P = 0.008). Seven-year clinical outcomes of patients with the gray-zone FFR were good. Furthermore, FFR-measured artery-related events in patients with the gray-zone FFR tended to occur less frequently than in patients with better FFR of 0.81–0.85. Optimal medical therapy is required for them, regardless of coronary stenosis severity and FFR.