Can CT perfusion guide patient selection for endovascular treatment of acute ischaemic stroke beyond the time window?


Modern neuroimaging techniques can accurately identify individuals with salvageable penumbra who present beyond the 8-hour timeframe of current selection criteria for intra-arterial therapies, suggests a small new study.

CT perfusion-guided patient selection for endovascular treatment of acute ischaemic stroke is safe and effective, report Aquilla Turk, Medical University of South Carolina, Charleston, USA and colleagues in the study published in September in the Journal of NeuroInterventional Surgery.

Results from the study have shown similar rates of good functional outcome and intracranial haemorrhage in patients with ischaemic stroke when endovascular treatment was carried out based on CT perfusion-guided selection rather than time-guided selection.

Current recommendations for the recanalisation of patients with acute ischaemic stroke are defined on the basis of time. So, conventionally, time from onset of acute ischaemic stroke has been the key selection criterion when administering intravenous and intra-arterial therapies.

Intravenous tissue plasminogen activator (tPA) administration is indicated within three hours of symptom onset, and newer evidence suggests it may be beneficial up to four and a half hours. Intra-arterial thrombolysis within six hours has been shown to be effective, while thrombectomy devices may be effective up to eight hours. However, the investigators point to recent evidence which suggests that image-based criteria may be useful for selecting patients for intra-arterial interventions.

The study assessed the use of CT perfusion -based criteria, regardless of time from symptom onset, in patient selection for intra-arterial treatment of ischaemic stroke.

The investigators prospectively assessed patients with ischaemic stroke who presented to the emergency department at the Medical University of South Carolina with a National Institute of Health Stroke Scale score of ≥8, regardless of time from symptom onset. They qualitatively assessed CT perfusion maps for the presence of penumbra and infarction. They then selected patients for mechanical aspiration of their occlusion using the Penumbra system from Concentric Medical/Stryker.

They also recorded the functional outcome using the modified Rankin scale at 90 days or the closest follow-up to 90 days.

There were 53 patients included in the study. The median time from symptom onset to groin vascular access was 6.3 hours. Eight patients (15%) had bleeding complications including subarachnoid haemorrhage, parenchymal haemorrhage and intraventricular haemorrhage. After CT perfusion-based selection, the patients were divided into two groups for analysis: ≤6h and >6h from symptom onset to endovascular procedure. No difference was found in functional outcome between the two groups (38.5% and 40.7% achieved 90-day modified Rankin scale ≤2, respectively (p=1.0) and 57.7% and 51.9% achieved 90-day modified Rankin scale≤3, respectively (p=0.785)). There was no difference in the rate of intracranial haemorrhage between the two groups (11.5 vs. 18.5, p=0.704).

Authors of the study wrote that the findings from their study suggest that endovascular reperfusion in ischaemic stroke may be effective and safe, and may allow patient selection that not solely based on time from symptom onset.