Ankle-Brachial Index for Risk Stratification in Patients With Symptomatic Peripheral Artery Disease With and Without Prior Lower Extremity Revascularization: Observations From the EUCLID Trial

Background: A reduced ankle-brachial index (ABI) is a measure of atherosclerosis and is associated with ischemic risk in the general population. Whether this relationship is maintained in peripheral artery disease after lower extremity revascularization (LER), which can modify ABI, is unknown. Methods: The EUCLID (Examining Use of Ticagrelor in Peripheral Artery Disease) enrolled 13 885 patients with symptomatic peripheral artery disease; 57% with prior LER, and 43% with ABI ≤0.80. The primary major adverse cardiovascular events (MACE) outcome was a composite of cardiovascular death, myocardial infarction, or ischemic stroke. Major adverse limb events (MALE) included acute limb ischemia and major amputation. An adjusted Cox proportional hazards model demonstrated a nonlinear relationship between ABI and outcomes. A restricted cubic spline model with 4 knots was developed to identify the best fitting model to describe the relationship between ABI and MACE and MALE risk. Results: Baseline ABI (mean±SD) was 0.77±0.21 in participants with prior LER and 0.63±0.14 in those without prior LER ( P P P P =0.0004) and MALE (hazard ratio, 1.27 [95% CI, 1.08–1.49]; P =0.003). Conclusions: Patients with established peripheral artery disease, particularly those with prior LER, have an increased risk of MACE and MALE. The ABI remains a strong predictor of MACE and MALE ischemic events with an inverse relationship below an ABI threshold for patients with and without prior LER. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01732822.