Objectives: (1) To evaluate the clinical outcomes of patients with moderate coronary lesions and borderline fractional flow reserve (FFR) measurements (between 0.75 and 0.80), comparing those who underwent coronary revascularization (CR) to those who had medical treatment (MT), and (2) to determine the predictive factors of major adverse cardiac events (MACE) at follow-up. Methods: A total of 107 consecutive patients (mean age 62 +/- 10 years) with at least one moderate coronary lesion (mean percent diameter stenosis 47 +/- 12\%) evaluated by coronary pressure wire with FFR measurement between 0.75 and 0.80 (mean 0.77 +/- 0.02) were included in the study. MACE [CR, myocardial infarction (MI), cardiac death) and the presence of angina were evaluated at follow-up. Results: Sixty-three patients (59\%) underwent CR and 44 patients (41\%) had MT, with no clinical differences between groups. At a mean followup of 13 +/- 7 months, MACE related to the coronary lesion evaluated by FFR were higher in the MT group compared with CR group (23\% vs. 5\%, P=0.005). Most MACE consisted of CRs, with no differences between groups in MI and cardiac death rate at follow-up. Both MT and FFR measurements in an artery supplying a territory with previous MI were independent predictive factors of MACE at follow-up, respectively (hazard ratio 5.2, 95\% CI 1.4-18.9, P=0.01; hazard ratio 4.1, 95\% CI 1.1-15.3, P=0.03). The presence of angina at follow-up was more frequent in the MT group compared with the CR group (41\% vs. 9\%, P=0.002). Conclusions: In patients with moderate coronary lesions and borderline FFR measurements deferral of revascularization was associated with a higher rate of MACE (CR) and a higher prevalence of angina at follow-up, especially in those with previous MI in the territory evaluated by FFR. Further prospective randomized studies should confirm whether or not an FFR cut-off point of 0.80 instead of 0.75 would be more appropriate for deferring CR in these cases. (C) 2008 Wiley-Liss, Inc.