Abstract 2215: Utility of Upfront Arterial and Perfusion Imaging among Ischemic Stroke Patients Presenting within the 4.5 hour Time Window

Abstract

Background: Although perfusion imaging is being evaluated as a tool to select acute ischemic stroke patients who are most likely to benefit from reperfusion therapies beyond the standard time windows, there is limited data on the utility of perfusion imaging within the IV thrombolytic time window. Methods: A new upfront comprehensive stroke imaging protocol was initiated at Emory University Hospital on July 1, 2010 to include CT angiography (CTA) of the head and neck and CT perfusion (CTP) of the head after non-contrast head CT. All patients presenting within 4.5 hours from last known normal time to Emory University Hospital with suspected stroke were prospectively identified from July 1 to December 31, 2010. Patients with POC Creatinine >1.7, allergy to contrast dye, current metformin use, pregnancy, intracranial hemorrhage (ICH) on non-contrast head CT or who declined consent were excluded from the protocol. Impact of CTA and CTP on the clinical management was recorded prospectively by stroke team members. Results: During the study period, 87 patients met eligibility criteria for the CTA/CTP protocol of which 83 (95%) underwent this upfront comprehensive imaging protocol and 30 (34%) received IV thrombolytic. CTA identified large vessel occlusion in 24 (29%) patients, including 5 with NIHSS ≤ 10 and 3 with NIHSS ≤ 5. CTP identified decreased cerebral blood volume > 1/3 of the ipsilateral MCA territory in 38% of anterior circulation large vessel occlusions. Overall, stroke team members reported that CTA and/or CTP aided their clinical management in 39 (47%) cases, including aiding in identification of a non-stroke diagnosis (n=18), triage to the NICU (n=9), early triage to endovascular therapy (n=4) and initiation of IV thrombolytic for low NIHSS with large vessel occlusion (n=3). There were no symptomatic ICHs and no contrast-induced nephropathy requiring dialysis during the study period. Door-to-needle time ≤ 60 minutes was achieved in only 23% of patients receiving IV thrombolysis during the study period but had improved to 39% in the subsequent 6 month period, similar to the pre-CTA/CTP protocol. Conclusions: An upfront CTA/CTP protocol to evaluate patients with acute ischemic stroke presenting within 4.5 hours aided stroke team decision making in nearly half of cases. Implementation of a CTA/CTP protocol was associated with a learning curve of 6 months before door-to-needle time ≤ 60 minutes returned to similar rates as the pre-CTA/CTP protocol.