Abstract 66: Ischemic Lesion Evolution and Hemorrhagic Transformation After Thrombolysis with Neuroprotection in FAST-MAG

Background: The frequency and range of early infarct signs in acute cerebral ischemia patients have been described in several 6-24 hour cohorts, but are incompletely characterized among under 2 hour presenting patients who actually proceed to receive IV tissue plasminogen activator (tPA). Prompt treatment with tPA improves outcomes after acute ischemic stroke, providing a platform to test promising neuroprotective strategies. We analyzed baseline and 24-hour imaging studies in an initial cohort of thrombolysis cases in the FAST-MAG trial of prehospital initiation of neuroprotection. Methods: Baseline and 24-hour CT/MRI studies acquired in 100 consecutive patients enrolled in FAST-MAG and treated with intravenous tPA were rated by two imaging experts for the presence of early ischemic changes (EIC), hyperdense vessel signs (HVS), ASPECTS score, white matter hyperintensities, prior infarction, lesion pattern and hemorrhagic transformation (HT), blind to all other data in the trial. Results: Among the 100 patients, mean age was 72±13 years; 44% were women; and median NIHSS was 14 (IQR 8-20). Initial imaging was obtained a mean of 91±29 minutes after last known well and routine post-thrombolysis imaging was obtained a mean of 23±13 hours later. Modality for initial scans was CT in 92% and MRI in 8%, and for follow-up scans CT in 63% and MRI in 37%. EIC were noted in 44%, including insular ribbon sign in 35%, lenticular obscuration in 28% and cortical effacement in 10%. HVS was visualized in 50%. Initial ASPECTS was median 9 (IQR 8-10) and 7 (IQR 4-9) at 24 hours. 24-hour lesion patterns were characterized as predominantly cortical in 50%, subcortical in 19%, scattered in 23% and no lesion in 8%. At 24 hours, ASPECTS correlated with NIHSS (R=-0.409, p Conclusions: Among patients imaged a mean of 1.5 hours after onset and then treated with thrombolysis, hyperdense vessel signs are present in one-half and early signs of ischemic parenchymal injury are present in nearly half, but are generally mild. Observed rates of HT were low. Serial imaging of patients treated with field neuroprotective therapies followed by post-arrival thrombolysis is often informative at initial and follow-up time points and has potential as biomarkers to interrogate treatment effects in prehospital neuroprotection studies.