Abstract
Objectives: Baseline-core-infarct volume is a critical factor in patient selection and outcome in acute ischemic stroke (AIS) before mechanical thrombectomy (MT). We determined whether oxygen extraction efficiency and arterial collaterals, two different physiologic components of the cerebral ischemic cascade, interacted to modulate baseline-core-infarct volume in patients with AIS-LVO undergoing MT triage.Methods: Between January 2015 and March 2018, consecutive patients with an AIS and M1 occlusion considered for MT with a baseline MRI and perfusion-imaging were included. Variables such as baseline-core-infarct volume [mL], arterial collaterals (HIR: TMax > 10 s volume/TMax > 6 s), high oxygen extraction (HOE, presence of the brush-sign on T2*) were assessed. A linear-regression was used to test the interaction of HOE and HIR with baseline-core-infarct volume, after including potential confounding variables.Results: We included 103 patients. Median age was 70 (58–78), and 63% were female. Median baseline-core-infarct volume was 32 ml (IQR 8–74.5). Seventy six patients (74%) had HOE. In a multivariate analysis both favorable HIR collaterals (p = 0.02) and HOE (p = 0.038) were associated with lower baseline-core-infarct volume. However, HOE significantly interacted with HIR (p = 0.01) to predict baseline-core-infarct volume, favorable collaterals (low HIR) with HOE was associated with small baseline-core-infarct whereas patients with poor collaterals (high HIR) and HOE had large baseline-core-infarct.Conclusion: While HOE under effective collateral blood-flow has the lowest baseline-core-infarct volume of all patients, the protective effect of HOE reverses under poor collateral blood-flow and may be a maladaptive response to ischemic stroke as measured by core infarctions in AIS-LVO patients undergoing MT triage.
Highlights
Mechanical thrombectomy (MT) is an effective treatment for acute ischemic stroke due to large-vessel occlusion (AIS-LVO) [1,2,3,4,5]
The study protocol was approved by the institutional review board and complied with the Health Insurance Portability and Abbreviations: AIS-LVO, Acute Ischemic Stroke due to Large-Vessel Occlusion; computed tomography (CT), Computed Tomography; hypoperfusion intensity ratio (HIR), Hypoperfusion Intensity Ratio; High oxygen extraction (HOE), High Oxygen Extraction; M1, Proximal Middle Cerebral Artery; magnetic resonance (MR), Magnetic Resonance imaging; MT, Mechanical Thrombectomy; NIHSS, National Institute of Health Stroke Scale; TMax, Time-to-Maximum
In this study of AIS-LVO patients undergoing MT triage, we found that HOE in patients with favorable collaterals is associated with small core infarctions at the time of presentation
Summary
Mechanical thrombectomy (MT) is an effective treatment for acute ischemic stroke due to large-vessel occlusion (AIS-LVO) [1,2,3,4,5]. MT eligible patients have a relatively small baseline-coreinfarct volume at the time of imaging evaluation, and patients with favorable arterial collaterals are more likely to present with a small core infarction [6, 7] and to have less core infarction growth [8]. Up to 40% of AIS-LVO patients may experience rapid early core infarct expansion, which often renders patients ineligible for MT at the time of imaging evaluation [9]. The hypoperfusion intensity ratio (HIR) is derived from computed tomography (CT) or magnetic resonance (MR) perfusion imaging and has emerged as a powerful imaging predictor of favorable collaterals, decreased core infarction growth, and favorable clinical outcomes [8, 10,11,12]. A low HIR (
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