Ravinder-Jeet Singh, MBBS, DM
Early and successful reperfusion leads to favourable outcome among patients with stroke having intracranial large artery occlusion. However, restoring blood flow to an infarcted tissue has a potential to induce reperfusion injury-related complications manifesting by development of malignant edema, intracerebral hemorrhage (ICH) or both. The risk is greater among those with larger pre-treatment infarct size, which is frequently defined using low ASPECTS scores (<6) or large cores (for example, >70-100 ml) on blood-flow imaging (CT/MR perfusion). Due to safety concerns, these patients were excluded from recent endovascular thrombectomy (EVT) trials. Contrary to general perception, recent literature demonstrates good safety of EVT in these patients and work by Kaesmacher et al1 is further addition to EVT safety and efficacy data in this group.
From a multicenter registry (BEYOND-SWIFT; N=2046), authors identified 237 patients who had ASPECTS 0-5 and underwent EVT. Overall, nearly equal proportion of patients had favorable outcome (mRS 0-3) and death (40.1% and 40.9%, respectively). Obviously, these patients had lower rates of favorable outcome than the group with ASPECTS 6-10 (40.1 vs 61.2%; P<0.001) and also had higher mortality (40.9 vs 21.2%; P<0.001), however, authors demonstrated no safety concerns of EVT with respect to rates of symptomatic ICH (7.2% vs 6.0%; P=0.466). The effect on all outcomes was clearly influenced by achievement of the successful reperfusion (TICI 2b/3), presence of which resulted in higher rates of favorable outcome, lower mortality and lower symptomatic ICH rates. On further inspection of the data, functional benefits were predominantly observed in ASPECTS 5 patients, nonetheless, mortality benefits were still observed in those with further lower ASPECTS scores (4 or even 0-3 group) when successful reperfusion was achieved. Patients with ASPECTS 0-5 had longer procedure duration (groin puncture to reperfusion), lower successful reperfusion rates and higher frequency of procedural complications during EVT than ASPECTS 6-10 patients. Larger clot burden and higher cervical artery dissection rates leading to procedural challenges might be few of the explanations for this observation.
Although results from HERMES collaboration2 also suggested treatment benefit among ASPECTS 0-5 patients, especially in ASPECTS 3-5, however, confidence intervals were large because of small number of patients and probably also because this group is more heterogeneous in terms of their treatment responses. Subgroup with poor response to EVT or potential harm needs to be identified in future studies. Present study certainly provides more real-world data to EVT safety in ASPECTS 0-5 patients. However, certain limitations should be noted. Only a third of patients (~35%) were ASPECTS 0-3, therefore, results largely demonstrate EVT safety in ASPECTS 4-5 patients. Further, functional benefits were predominantly noted in ASPECT 5 than 0-4, though, the latter group did have survival benefits from successful reperfusion. There was no central adjudication of ASPECTS and mTICI scores, which could have potentially introduced measurement error. Despite these limitations, the results support EVT as a potential treatment option for patients with large vessel occlusion and ASPECTS <6 and needs to be tested in randomized trials.
References
- Kaesmacher J, Chaloulos-Iakovidis P, Panos L, Mordasini P, Michel P, Hajdu SD, et al. Mechanical Thrombectomy in Ischemic Stroke Patients With Alberta Stroke Program Early Computed Tomography Score 0-5. Stroke. 2019;50:880-888.
- Román LS, Menon BK, Blasco J, Hernández-Pérez M, Dávalos A, Majoie CBLM, et al; HERMES collaborators. Imaging features and safety and efficacy of endovascular stroke treatment: a meta-analysis of individual patient-level data. Lancet Neurol. 2018;17:895-904. doi: 10.1016/S1474-4422(18)30242-4.
