Ankle-Brachial Index and cardiovascular events in atrial fibrillation

Atrial 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.