Background and Purpose— Remote ischemic preconditioning is neuroprotective in models of acute cerebral ischemia. We tested the effect of prehospital rPerC as an adjunct to treatment with intravenous alteplase in patients with acute ischemic stroke. Methods— Open-label blinded outcome proof-of-concept study of prehospital, paramedic-administered rPerC at a 1:1 ratio in consecutive patients with suspected acute stroke. After neurological examination and MRI, patients with verified stroke receiving alteplase treatment were included and received MRI at 24 hours and 1 month and clinical re-examination after 3 months. The primary end point was penumbral salvage, defined as the volume of the perfusion–diffusion mismatch not progressing to infarction after 1 month. Results— Four hundred forty-three patients were randomized after provisional consent, 247 received rPerC and 196 received standard treatment. Patients with a nonstroke diagnosis (n=105) were excluded from further examinations. The remaining patients had transient ischemic attack (n=58), acute ischemic stroke (n=240), or hemorrhagic stroke (n=37). Transient ischemic attack was more frequent ( P =0.006), and National Institutes of Health Stroke Scale score on admission was lower ( P =0.016) in the intervention group compared with controls. Penumbral salvage, final infarct size at 1 month, infarct growth between baseline and 1 month, and clinical outcome after 3 months did not differ among groups. After adjustment for baseline perfusion and diffusion lesion severity, voxelwise analysis showed that rPerC reduced tissue risk of infarction ( P =0.0003). Conclusions— Although the overall results were neutral, a tissue survival analysis suggests that prehospital rPerC may have immediate neuroprotective effects. Future clinical trials should take such immediate effects, and their duration, into account. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00975962.

Campbell, B. C.V. et al. (2019) Penumbral imaging and functional outcome in patients with anterior circulation ischaemic stroke treated with endovascular thrombectomy versus medical therapy: a meta-analysis of individual patient-level data.ABSTRACT Background: CT-perfusion (CTP) and MRI may assist patient selection for endovascular thrombectomy. We aimed to establish whether imaging assessments of ischaemic core and penumbra volumes were associated with functional outcomes and treatment effect.

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Background and Purpose-Perfusion-weighted imaging can predict infarct growth in acute stroke and potentially be used to select patients with tissue at risk for reperfusion therapies. However, the lack of consensus and evidence on how to best create PWI maps that reflect tissue at risk challenges comparisons of results and acute decision-making in trials. Deconvolution using an arterial input function has been hypothesized to generate maps of a more quantitative nature and with better prognostic value than simpler summary measures such as time-to-peak or the first moment of the concentration time curve. We sought to compare 10 different perfusion parameters by their ability to predict tissue infarction in acute ischemic stroke. Methods-In a retrospective analysis of 97 patients with acute stroke studied within 6 hours from symptom onset, we used receiver operating characteristics in a voxel-based analysis to compare 10 perfusion parameters: time-to-peak, first moment, cerebral blood volume and flow, and 6 variants of time to peak of the residue function and mean transit time maps. Subanalysis assessed the effect of reperfusion on outcome prediction. Results-The most predictive maps were the summary measures first moment and time-to-peak. First moment was significantly more predictive than time to peak of the residue function and local arterial input function-based methods (PϽ0.05), but not significantly better than conventional mean transit time maps. Conclusion-Results indicated that if a single map type was to be used to predict infarction, first moment maps performed at least as well as deconvolved measures. Deconvolution decouples delay from tissue perfusion; we speculate this negatively impacts infarct prediction.