Objective: Long term graft surveillance is presently the standard of care for following patients who have undergone infra-inguinal bypass grafting. However, the role of intervention in asymptomatic patients with increased graft velocities has yet to be defined. The goal of the current study was to determine the natural history of increased graft velocities in asymptomatic patients following infra-inguinal bypasses.Methods: We reviewed surveillance duplex ultrasound studies in all patients who underwent infra-inguinal bypasses from October 2007-December 2020. Patients with symptomatic stenoses or occlusions were excluded. Additionally, grafts with only one follow-up duplex, stenoses in native arteries, or graft occlusions were excluded. Results: We identified 60 infra-inguinal grafts with asymptomatic stenoses on duplex ultrasound a mean 0.97±1.24 years after the original bypass. Of these, 44 (73%) were saphenous vein bypasses. Stenoses were found at the proximal anastomoses in 21 grafts (35%), proximal graft in 10 (17%), mid graft in 5 (8%), distal graft in 5 (8%), distal anastomoses in 16 (27%), and both proximal/distal anastomoses in 3 (5%) with mean peak systolic velocity of 387± 133 cm/second. Thirty-one grafts underwent immediate intervention and 29 were observed. Of these 31 grafts, 26 (84%) were patent, 2 had occluded, with mean follow-up of 7.7 months, and 3 had no follow-up. Ten of these grafts required additional intervention. Of the 29 grafts observed, 17 (59%) had progression of lesion on surveillance duplex, and 12 (41%) had a stable lesion or lesion regression at 15 months follow-up. Out of the 17 grafts where stenosis had progressed, 10 of them (58%) required an intervention. Thirteen (45%) progressed to symptoms; of these, 6 grafts had occluded. The immediate intervention group had higher lesion peak systolic velocity (428 cm/second vs. 293cm/second; p<0.0001). All five grafts with mid-graft stenoses (4 retained valves and 1 stenosis in cephalic/saphenous vein composite graft) were in the immediate intervention group. Grafts in the group without immediate intervention were more likely to have stenosis at the proximal anastomosis compared to those with immediate intervention (55% vs. 16%; p<0.01). Conclusion: Most patients with observed asymptomatic stenoses had lesion progression on ultrasound, with many progressing to symptoms. Asymptomatic stenoses on surveillance duplex ultrasound should be treated to maintain patency or followed with short interval surveillance to detect progression prior to graft occlusion.
