Abstract 3438: Intracranial Arterial Occlusion and Extent of Hypoattenuation on CT Angiography Source Images may Modify the Benefit of Thrombolysis

Background: CT angiography source images (CTASI) improve diagnostic accuracy for ischemic brain infarction compared to non-contrast CT (NCCT). We studied whether CTASI alone or combined with the CTA occlusion status may improve patient selection for thrombolysis in an extended time window. Methods: We prospectively observed patients presenting with anterior circulation ischemic stroke within 12 hours from symptom onset and an NIHSS score ≥ 3. All patients underwent cranial NCCT and CTA. Patients were treated with intravenous and/or intra-arterial thrombolysis at the discretion of the treating stroke neurologist and neuroloradiologist. We determined intracranial occlusion status and applied the Alberta Stroke Program Early CT Score (ASPECTS) to CTASI. Primary clinical outcome measure was independent outcome at 3 months, defined as mRS scores 0-2. We calculated unadjusted risk ratios to assess the effect of thrombolysis on functional outcome in patients with: 1) minor ischemic changes on CTASI (CTASI-ASPECTS >5) and 2) patients with minor ischemic changes on CTASI and middle cerebral artery (MCA) occlusion. Results: We enrolled 102 patients with a mean age of 71 +/- 12 years, median onset-to-CTA time of 112,5 (range 37-898) min, a median NIHSS score of 9.5 (3-39), and a median CTASI-ASPECTS of 8. Sixty-two patients (61%) received any thrombolysis (56 IV, 5 IV/IA, 1 IA). MCA occlusion was present in 57 patients (56%), 80/101 (80%) assessable patients had a CTASI-ASPECTS >5 and 37/101 (37%) patients had a CTASI-ASPECTS >5 in the presence of a MCA occlusion. At 3 months, 52 (51%) patients had an independent functional outcome. When patients with CTA-SI ASPECTS > 5 received thrombolysis, 30/46 (65%) achieved an independent functional outcome, whereas 20/35 (57%) without thrombolysis were functionally independent (RR 1.1, CI 95 0.8-1.6). In patients with CTASI-ASPECTS > 5 and additional MCA-occlusion, 13/24 (54%) with thrombolysis and 3/13 (23%) without thrombolysis achieved an independent functional outcome (RR 2.3, CI 95 0.8-6.8). Conclusion: In our non-randomized study, the extent of CTASI hypoattenuation alone did not identify patients benefiting from thrombolysis. In the presence of an MCA-occlusion, however, CTASI might identify patients with benefit from thrombolysis in an extended time window.