BackgroundThe neutrophil–lymphocyte ratio (NLR) is emerging as an important biomarker of acute physiologic stress in a myriad of medical conditions, and is a confirmed poor prognostic indicator in COVID-19.ObjectiveWe sought to describe the role of NLR in predicting poor outcome in COVID-19 patients undergoing mechanical thrombectomy for acute ischemic stroke.MethodsWe analyzed NLR in COVID-19 patients with large vessel occlusion (LVO) strokes enrolled into an international 12-center retrospective study of laboratory-confirmed COVID-19, consecutively admitted between March 1, 2020 and May 1, 2020. Increased NLR was defined as ≥7.2. Logistic regression models were generated.ResultsIncidence of LVO stroke was 38/6698 (.57%). Mean age of patients was 62 years (range 27–87), and mortality rate was 30%. Age, sex, and ethnicity were not predictive of mortality. Elevated NLR and poor vessel recanalization (Thrombolysis in Cerebral Infarction (TICI) score of 1 or 2a) synergistically predicted poor outcome (likelihood ratio 11.65, p = .003). Patients with NLR > 7.2 were 6.8 times more likely to die (OR 6.8, CI95% 1.2–38.6, p = .03) and almost 8 times more likely to require prolonged invasive mechanical ventilation (OR 7.8, CI95% 1.2–52.4, p = .03). In a multivariate analysis, NLR > 7.2 predicted poor outcome even when controlling for the effect of low TICI score on poor outcome (NLR p = .043, TICI p = .070).ConclusionsWe show elevated NLR in LVO patients with COVID-19 portends significantly worse outcomes and increased mortality regardless of recanalization status. Severe neuro-inflammatory stress response related to COVID-19 may negate the potential benefits of successful thrombectomy.