Low and Borderline Ankle Brachial Index is Associated with Intracranial Aneurysms – A Retrospective Cohort Study

Background and Aims A low ankle-brachial index (ABI) is associated with a higher risk of cardiovascular diseases, stroke, and systemic inflammation. Intracranial aneurysms (IAs) share similar risk factors with other cardiovascular diseases. However, the association between low ABI and IAs lacks sufficient investigation. Methods This retrospective study reviewed 2751 patients who had ABI measurements at a tertiary hospital from January 2011 to December 2013. Patients with available cerebrovascular imaging or a diagnosis of ruptured IA were included in the study (n=776) to examine the association between ABI and saccular IAs. The patients were classified into four groups: low ABI (≤0.9, n=464), borderline ABI (0.91-0.99; n=47), high ABI (>1.4, n=57), and normal ABI (1.00-1.40; n=208). Results The prevalence of IAs was 20.3% (18.1% unruptured IAs) in the low ABI group, 14.9% (12.8% unruptured IAs) in the borderline ABI group, 7.0 % (5.3% unruptured IAs) in the high ABI group, and 2.4% (1.9% unruptured IAs) in the normal ABI group ( p< 0.001). Sex- and age-adjusted multinomial regression, including clinically relevant variables, revealed that low ABI (odds ratio [OR], 11.33; 95% confidence interval [CI], 4.08-31.51; p< 0.001) and borderline ABI (0.91-0.99) (OR, 7.13; 95% CI, 1.91-26.63; p= 0.004) were the only variables significantly associated with unruptured IAs. Conclusions The prevalence of unruptured IAs was 9-fold higher in the low ABI group and nearly 7-fold higher in the borderline ABI group when compared to the normal ABI group. ABI measurements could be clinically relevant for identifying individuals at higher risk of IAs and may help guide screening and preventive strategies.