The Global Anatomic Staging System Does Not Predict Limb Based Patency of Tibial Endovascular Interventions

Abstract

Anatomic grading systems have historically been poor predictors of patency after endovascular tibial interventions. The Global Vascular Guidelines proposed a new Global Anatomic Staging System (GLASS) to estimate one-year limb-based patency (LBP). The purpose of this study was to determine the association of GLASS with LBP following endovascular tibial interventions. We included all patients presenting to our multidisciplinary diabetic limb preservation service between 01/2012 and 8/2020 who underwent first-time endovascular tibial revascularization for chronic limb-threatening ischemia. Diagnostic angiograms were reviewed to define the preferred target artery pathway and assign a GLASS stage to each treated limb. One-year LBP was calculated and compared across GLASS stages using Kaplan-Meier curves with log-rank tests and Cox proportional hazards models. We performed tibial revascularization in 96 limbs (5.2% rest pain, 56.3% ulcer, 37.5% gangrene), including isolated tibial interventions in 61.5% and tibial + femoropopliteal interventions in 38.5%. 15.6% of limbs were GLASS stage 1, 28.1% were GLASS stage 2, and 56.3% were GLASS stage 3. Overall, one-year LBP was 43.2 ± 6.3%, and did not differ significantly across GLASS stages (P = 0.42). The hazard ratio for failed LBP was 1.94 (95% CI 0.70-5.41) for GLASS stage 2 and 1.49 (95% CI 0.56-3.94) for GLASS stage 3 limbs (versus GLASS stage 1). When analyzed excluding the calcium modifier, LBP remained similar across GLASS stages (P = 0.72). Major amputation was uncommon, occurring in 9.3 ± 3.4% of limbs at one year, and did not significantly differ by GLASS stage (P = 0.98). The Global Anatomic Staging System did not predict limb-based patency following tibial endovascular interventions. Given the low major amputation rates in this cohort, anatomic complexity should not preclude endovascular limb salvage efforts below the knee.