Ankle-Brachial Index and cardiovascular events in atrial fibrillation: The ARAPACIS study

Atrial fibrillation (AF) patients are at high risk for thrombotic and vascularevents related to their cardiac arrhythmia and underlying systemicatherosclerosis. Ankle-Brachial Index (ABI) is a non-invasive tool in evaluating systemic atherosclerosis, useful in predicting cardiovascular events in generalpopulation; no data are available in AF patients. ARAPACIS is a prospectivemulticentre observational study performed by the Italian Society of InternalMedicine, analysing association between low ABI (≤ 0.90) and vascular events inNVAF out- or in-patients, enrolled in 136 Italian centres. A total of 2,027non-valvular AF (NVAF) patients aged > 18 years from both sexes followed for amedian 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 % malepatients. A total of 176 patients (8.7 %) experienced a vascular event, with acumulative incidence of 3.81 %/patient-year. ABI≤ 0.90 was more prevalent inpatients 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). Thislatter 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 betweenlow ABI and stroke/transient ischaemic attack (p=0.91). In conclusion, low ABI isuseful to predict MI and vascular death in NVAF patients and may independentlyfacilitate cardiovascular risk assessment in NVAF patients.