SummaryAtrial fibrillation (AF) patients are at high risk for thrombotic and vascular events related to their cardiac arrhythmia and underlying systemic atherosclerosis. Ankle-Brachial Index (ABI) is a non-invasive tool in evaluating systemic atherosclerosis, useful in predicting cardiovascular events in general population; no data are available in AF patients. ARAPACIS is a prospective multicentre observational study performed by the Italian Society of Internal Medicine, analysing association between low ABI (≤0.90) and vascular events in NVAF out- or in-patients, enrolled in 136 Italian centres. A total of 2,027 non-valvular AF (NVAF) patients aged > 18 years from both sexes followed for a median time of 34.7 (interquartile range: 22.0–36.0) months, yielding a total of 4,614 patient-years of observation. Mean age was 73 ± 10 years old with 55% male patients. A total of 176 patients (8.7%) experienced a vascular event, with a cumulative incidence of 3.81%/patient-year. ABI≤ 0.90 was more prevalent in patients with a vascular event compared with patients free of vascular events (32.2 vs 20.2%, p< 0.05). On Cox proportional hazard analysis, ABI≤ 0.90 was an independent predictor of vascular events (hazard ratio (HR): 1.394, 95% confidence interval (CI): 1.042–1.866; p=0.02), vascular death (HR: 2.047, 95% CI: 1.255-3.338; p=0.004) and MI (HR: 2.709, 95%> CI: 1.485-5.083; p=0.001). This latter association was also confirmed after excluding patients with previous MI (HR: 2.901, 95% CI: 1.408-5.990, p=0.004). No association was observed between low ABI and stroke/transient ischaemic attack (p=0.91). In conclusion, low ABI is useful to predict MI and vascular death in NVAF patients and may independently facilitate cardiovascular risk assessment in NVAF patients.Note: The review process for this paper was fully handled by C. Weber, Editor in Chief.Listed in the Supplementary Online Appendix Material which is available online at www.thrombosis-online.com.