The Utility of Ankle-Brachial Index as a Predictor of Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

Abstract

Delayed cerebral ischemia (DCI) can cause significant morbidity and mortality in patients suffering from aneurysmal subarachnoid hemorrhage (SAH). Because arterial stiffness has been correlated with vascular risk factors, we evaluated whether the ankle-brachial index (ABI), the ratio of the ankle and brachial systolic blood pressures, can predict DCI. In a prospective cohort study, we measured the ABIs of 24 patients with aneurysmal SAH during the weeks after SAH. Angiographic vasospasm was evaluated via diagnostic cerebral angiograms. Transcranial Doppler (TCD) was used to assess associations among ABI, DCI, and angiographic vasospasm. Patients were evaluated on the basis of the presence or absence of DCI (days 3-14 after SAH). Demographic and history factors were similar between the DCI and non-DCI groups. Patients in the DCI group had a greater modified Fisher grade (P= 0.029) and were more likely to have been treated via clipping (P= 0.032) and to demonstrate angiographic vasospasm (P= 0.009). Mean TCD values in the 2 groups were significantly different after day 5 in varied arterial distributions (P < 0.05). ABI values in the DCI group were significantly lower on posthemorrhage days 2-13 and when averaged over the 2-week study period (P < 0.05). An average ABI >1.045 ondays 2-7 was 85% sensitive and 82% specific for predicting absence of DCI. In this small single-center study, lower ABI values were strongly associated with SAH-induced DCI, which may provide a tool for managing DCI in aneurysmal SAH.