Validation Of The Global Limb Anatomical Staging System In First-time Lower Extremity Revascularization
Patric Liang, MD, Christina L. Marcaccio, MD, Jeremy D. Darling, MS, Daniel Kong, BA, Vaishnavi Rao, BS, Nicholas J. Swerdlow, MD, Marc Schermerhorn, MD.
Beth Israel Deaconess Medical Center, Boston, MA, USA.
ObjectiveThe Society for Vascular Surgery developed the Global Limb Anatomical Staging System (GLASS) as a new anatomic classification scheme for grading the severity of chronic limb threatening ischemia (CLTI). We evaluated the ability of this grading system to determine major adverse limb events following lower extremity revascularization.
MethodsWe performed a single-institutional retrospective review all 1,299 patients undergoing first-time open or endovascular revascularization for CLTI from 2005-2014. Based on femoropopliteal and infrapopliteal angiographic images, limbs were stratified into GLASS Stages I, II, and III. The primary outcome was reintervention, major amputation (below or above knee amputation), or restenosis (>3.5x step-up by duplex criteria) events (RAS). Kaplan-Meier estimates were used to determine event rates through 5 years.
ResultsOf all patients undergoing first-time revascularization, 1,180 patients (91%) had imaging available for GLASS grading. Compared to GLASS Stage I disease (N=267, 23%), Stage II (N=367, 31%) and Stage III (N=546, 42%) were associated with higher risk of RAS at 1-year (Stage I: 33% vs. Stage II: 48% vs. Stage III: 53%) and 5-years follow-up (Stage I: 45%, reference; Stage II: 65%, HR 1.7 [1.3-2.2], P<.001; Stage III: 69%, HR 2.3 [1.7-2.9], P < .001). These differences were mainly driven by reintervention and restenosis rather than by major amputation. Five-year mortality was similar in Stage II and III compared to Stage I disease (Stage I: 40%, reference; Stage II: 45%, HR 1.1 [0.8-1.4], P=.69; Stage III: 49%, HR 1.2 [1.0-1.6], P=.11). For all attempted endovascular interventions, failure to cross a target lesion increased with advancing GLASS Stages (Stage I: 4.5% vs. Stage 2: 6.3% vs. Stage 3: 13.3%, P<.01). Compared to open bypass (N=552, 46.8%), endovascular intervention (N=628, P=53.3%) was associated with higher rate of 5-year RAS for GLASS Stages I (49 vs 34%, P = .03; HR 1.9 [1.1-3.5], P=.03), II (69 vs 52%, P < .01, HR 1.7 [1.2-2.5], P<.01), and III (83 vs 61%, HR 1.5 [1.2-2.0], P<.01).
ConclusionsIn patients undergoing first-time lower extremity revascularization, the SVS GLASS anatomic classification scheme can be used to predict technical success, reintervention, and restenosis, but not major amputation. Bypass appears to have the better long-term outcomes compared to endovascular intervention in all GLASS stages.
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