Abstract T P177: Non-dominant Vertebral Artery With Higher Resistance Flow Pattern Is A Risk Factor For Ischemic Stroke

Background and aims: The diameters of the vertebral arteries (VAs) are very often unequal and the larger artery is called ‘dominant’. We investigated whether the hemodynamic parameters differ between the ‘dominant’ and ‘non-dominant’ variants. Methods: Consecutive patients who underwent computed tomographic angiography (CTA) of cervical and intracranial arteries, cervical duplex (CDU) and transcranial Doppler (TCD) ultrasonography were included. VA diameters (cervical and intracranial segments) were measured on CTA. Flow velocities recorded were peak systolic (PSV), end-diastolic (EDV), mean flow (MFV). Pulsatility index (PI) and ratio of distal-to-proximal VAs were computed. Results: Of the total 501 patients admitted during 2012 with acute ischemic stroke, both CTA and ultrasound data were available for VAs for 161 (32%). The dominant VA was more frequent on the left side (p<0.01). Non-dominant VAs were found to have lower MFV (27cm/s versus 38cm/s; p<0.01) and higher PI (1.27 versus 1.0; p<0.01) as compared to the dominant variant. In most patients, proximal basilar artery was noted to be on the side of non-dominant artery. Posterior inferior cerebellar artery territory infarcts and lateral medullary infarcts were noted in 38 (7.6%) patients. These infarcts were noted more commonly on the same side as the non-dominant intracranial VA side (p<0.01), especially when associated with low MFV (p<0.01) and high PI (p<0.01). Conclusions: The risk of ischemic stroke in VA territory is higher with the non-dominant artery, especially when it is associated with higher-resistance flow pattern.