Validation of the Global Anatomic Staging System (GLASS) using the BASIL-1 Best Endovascular Therapy Cohort

Abstract

Background: Global Anatomic Staging System (GLASS) is a new anatomical staging system proposed in the Global Vascular Guidelines (GVG) on Chronic Limb Threatening Ischaemia (CTLI) that aims to correlate the angiographic pattern of disease with immediate technical failure (ITF) and clinical outcomes following infra-inguinal endovascular revascularisation. We aimed to clarify the relationship between GLASS, ITF and clinical outcomes in the Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL-1) trial. Methods: We examined the relationship between ITF, amputation free survival (AFS), limb salvage (LS), and major adverse limb events (MALE) in 213 patients (43% diabetes) who underwent angioplasty (n = 159, femoro-popliteal [FP] only; n= 54, infra-popliteal [IP] ± FP) as their first revascularisation procedure in BASIL-1 and in whom baseline angiograms were available for GLASS staging. Results: There were 43, 54, and 116 patients in GLASS stage I, II, and III respectively. GLASS stage and diabetes were predictors of ITF, which occurred in 22% of patients. In the FP only group, GLASS stage III was associated with significantly worse AFS (vs stage I, p=0.04), LS (vs stage II, p=0.03) and MALE (vs stage I, p=0.05). There was no relationship between these outcomes and GLASS in the IP ± FP group. Conclusion: This is the first study to attempt to validate GLASS in a cohort of CTI patients undergoing infra-inguinal revascularisation and suggests GLASS may be a useful predictor of ITF and longer-term clinical outcomes so allowing better choice of initial revascularisation procedure and stratification of patients.