Descriptive Analysis of Amputation-Free Survival After First Time Infra-Inguinal Bypass Occlusion

Introduction: Occlusion after infra-inguinal bypass surgery for peripheral artery disease is a major complication with potentially devastating consequences. In this descriptive analysis, we sought to describe the natural history and explore factors associated with long-term major amputation-free survival following occlusion of a first-time infra-inguinal bypass.

Methods: Using a prospective database from a tertiary care vascular center, we conducted a retrospective cohort study of all patients with peripheral artery disease who underwent a first-time infra-inguinal bypass and subsequently suffered a graft occlusion (1997-2021). The primary outcome was longitudinal rate of major amputation-free survival after bypass occlusion. Cox proportional hazard models were used to generate hazard ratios (HRs) and 95% confidence intervals (CIs) to explore predictors of outcomes.

Results: Of the 1318 first-time infra-inguinal bypass surgeries performed over the study period, 255 bypasses occluded and were included in our analysis. Mean age was 66.7 (12.6) years, 40.4% were female, and indication for index bypass was chronic limb threatening ischemia (CLTI) in 89.8% (n = 229). 48.2% (n = 123) of index bypass conduits used great saphenous vein, 29.0% (n = 74) prosthetic graft, and 22.8% (n = 58) an alternative conduit. Median (interquartile range) time to bypass occlusion was 6.8 (2.3-19.0) months, and patients were followed for median of 4.3 (1.7-8.1) years after bypass occlusion. Following occlusion, 38.04% underwent no revascularization, 32.94% graft salvage procedure, 25.1% new bypass, and 3.92% native artery recanalization. Major amputation-free survival following occlusion was 56.9% (50.6%-62.8%) at 1 y, 37.1% (31%-43.3%) at 5 y, and 17.2% (11.9%-23.2%) at 10 y. In multivariable analysis, factors associated with lower amputation-free survival were older age, female sex, advanced cardiorenal comorbidities, CLTI at index procedure, CLTI at time of occlusion, and distal index bypass outflow. Initial treatment after occlusion with both a new surgical bypass (HR 0.44, CI: 0.29-0.67) or a graft salvage procedure (HR 0.56, CI: 0.38-0.82) showed improved amputation-free survival. One-year rate of major amputation or death were 59.8% (50.0%-69.6%) for those who underwent no revascularization, 37.9% (28.7%-49.0%) for graft salvage, and 26.7% (17.6%-39.5%) for new bypass.

Conclusions: Long-term major amputation-free survival is low after occlusion of a first-time infra-inguinal bypass. While several nonmodifiable risk factors were associated with lower amputation-free survival, treatment after graft occlusion with either a new bypass or a graft salvage procedure may improve longitudinal outcomes.