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.