327 The Incidence of Clinically Significant Magnetic Resonance Angiography Findings for Transient Ischemic Attack Patients in the Observation Unit

Abstract

Background: A transient ischemic attack (TIA) is no longer considered to be a benign event, rather it is a serious warning for an impending stroke. Studies show that this “transient event” is associated with a 90-day risk of a stroke in approximately 10% of people, with half of these strokes occurring within 48 hours of the inciting event. This critical statistic favors the need for close monitoring and expeditious neurologic workup. With advancements in technology one of the major diagnostic studies for cerebrovascular accident (CVA) is magnetic resonance angiography (MRA). MRA is advantageous as it can detect hyperacute and minute ischemic lesions as well as lesions in the posterior fossa, in addition to aneurysms and arteriovenous malformations. This study serves to evaluate the incidence of clinically significant MRA findings following a TIA, in our emergency department observation unit (EDOU). To determine if there is a significant amount of patients with clinically relevant findings on MRA that may have otherwise gone undiagnosed. Clinical significance is defined as any finding that warrants further workup or intervention. This descriptive study was a retrospective chart analysis of 684 asymptomatic TIA patients admitted to the EDOU, over a 20-month period. Patients were divided by significant or no significant findings for either brain or neck MRA or both. There were no significant findings for either the brain or neck MRA in 70.8% (n=484) of patients. 9.8% (n=67) had significant findings for only the neck MRA. 12.0% (n=82) of patients had significant findings for only the brain MRA. 7.5% (n=51) had significant findings for both brain and neck MRA. Significant findings included moderate to severe vascular stenosis and/or occlusion of the vertebral arteries, carotid, aneurysms (saccular and fusiform), subclavian steal syndrome, and thyroid nodules. Clinically significant findings were noted in 29.4% of the 684 patients. With the use of MRA of the brain and neck, we are discovering more clinically significant findings that may have gone years undiagnosed. Based on this data, it seems fitting that the use of MRI of the brain with MRA of the brain and neck should be utilized for evaluation of TIA patients when able, thus replacing prior workups such as, carotid ultrasound.