Ankle-Brachial Index

* **Definition:** ratio of ankle systolic pressure to brachial systolic pressure.
* **Normal values:** 1.00–1.40.
* **peripheral**Peripheral arterial disease (PAD) diagnosis:** <0.90An indicatesankle-brachial peripheralindex arterial(ABI) disease;<0.90 indicates PAD; <0.50 indicates severe ischemia.ischemia [@svs2024-writing] [@uyagu2022-quality].
* **Noncompressible arteries:** Values >1.40 suggest medial arterial calcificationcalcification, (commonwhich is common in patients with diabetes mellitus and chronic kidney disease).disease (CKD) [@chinese2025]. In such cases, measure toe pressures and toe-brachial index instead.(TBI) instead [@svs2024-writing].
* **Exercise testing:** If symptoms suggest PAD but resting ankle-brachial index (ABI)ABI is normal, perform post-exercise ABI. A decrease ≥20% in ABI or ≥30 mmHg drop in ankle pressure supports the diagnosis.diagnosis [@svs2024-writing].
* **Guidelines:** AHA/ACCThe (2016)2024 multi-society guideline (ACC/AHA/SVS/SIR/VESS) and the ESC (2017) recommend ABI as the first-line screening,screening tool for PAD, with exercise ABI and toe-brachialTBI indexindicated (TBI)for whenspecific indicated.clinical [@aboyans2012]scenarios [@aha2016]where resting ABI is non-diagnostic [@svs2024-writing] [@esc2017] [@uyagu2022-quality]. [@aboyans2012] [@aha2016] [@potier2011]