Abstract
BackgroundThe presence of metabolically viable brain tissue that may be salvageable with rapid cerebral blood flow restoration is the fundament rationale for reperfusion therapy in patients with large vessel occlusion stroke. The effect of endovascular treatment (EVT) on functional outcome largely depends on the degree of recanalization. However, the relationship of recanalization degree and penumbra salvage has not yet been investigated. We hypothesized that penumbra salvage volume mediates the effect of thrombectomy on functional outcome.Methods99 acute anterior circulation stroke patients who received multimodal CT and underwent thrombectomy with resulting partial to complete reperfusion (modified thrombolysis in cerebral infarction scale (mTICI) ≥ 2a) were retrospectively analyzed. Penumbra volume was quantified on CT perfusion and penumbra salvage volume (PSV) was calculated as difference of penumbra and net infarct growth from admission to follow-up imaging.ResultsIn patients with complete reperfusion (mTICI ≥ 2c), the median PSV was significantly higher than the median PSV in patients with partial or incomplete (mTICI 2a–2b) reperfusion (median 224 mL, IQR: 168–303 versus 158 mL, IQR: 129–225; p < 0.01). A higher degree of recanalization was associated with increased PSV (+ 63 mL per grade, 95% CI: 17–110; p < 0.01). Higher PSV was also associated with improved functional outcome (OR/mRS shift: 0.89; 95% CI: 0.85–0.95, p < 0.0001).ConclusionsPSV may be an important mediator between functional outcome and recanalization degree in EVT patients and could serve as a more accurate instrument to compare treatment effects than infarct volumes.
Highlights
Mechanical thrombectomy (MT) in acute ischemic stroke substantially improves functional outcome in patients with large vessel occlusion [18, 34]
The American Heart Association (AHA) guidelines recommend a score of ≥ 2b on the modified Thrombolysis in Cerebral Infarction scale as the angiographic goal of MT [29, 30]
All ischemic stroke patients admitted in the aforementioned time period were screened based on the following a priori defined inclusion criteria: (1) acute anterior circulation stroke in the territory of the middle cerebral artery (MCA) and MCA occlusion; (2) multimodal computed tomography (CT) imaging protocol at admission including CT Angiography (CTA) and CT Perfusion (CTP); (3) known time window from symptom onset to admission imaging; (4) follow-up CT (FCT) 24 h after admission; (5) admission
Summary
Mechanical thrombectomy (MT) in acute ischemic stroke substantially improves functional outcome in patients with large vessel occlusion [18, 34]. The effect of endovascular treatment on functional outcome highly depends on the degree of recanalization as exemplified in previous studies [15, 20, 21]. A meta-analysis found an incremental association between the degree of recanalization and clinical outcome [21]. A wide range of outcome is still evident even in cases of successful reperfusion, indicating that outcome is completely mediated by further baseline and procedural covariates [9, 21]. It remains uncertain how the volume of penumbra salvage (PSV) mediates the effect of thrombectomy on functional outcome. We hypothesized that PSV is directly linked to functional outcome
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