Introduction: This study aimed to identify predictors of 90-day good functional outcome (GFO) in patients with acute ischaemic stroke (AIS) who were treated with mechanical thrombectomy but did not achieve a delayed neurological improvement (DNI).
Clinical rationale for the study: In-hospital neurological improvement in patients with AIS is consistently associated with long- -term GFO. Patients who experience neither early nor delayed neurological improvement can still achieve long-term GFO, but predictors of such an outcome have not been studied.
Material and methods: This single-centre retrospective study involved 307 patients with anterior circulation AIS treated with mechanical thrombectomy. Multiple clinical, biochemical, radiological, and treatment-related variables were collected and analysed. DNI on day 7 was defined as at least a 10-point reduction in the National Institutes of Health Stroke Scale (NIHSS) score or NIHSS score < 2. GFO on day 90 was defined as a modified Rankin Scale (mRS) score ≤ 2. We compared the characteristics of patients with and without DNI, with special attention paid to patients who achieved 90-GFO despite a lack of DNI. Multivariate analyses were then performed to establish independent predictors of 90-day GFO among patients without DNI.
Results: DNI occurred in 150 out of 307 patients (48.7%) and significantly increased the odds for 90-day GFO (odds ratio [OR]: 13.99; p < 0.001). Among patients without DNI, 41.4% achieved 90-day GFO. Younger age (OR: 0.96; 95% confidence interval [CI]: 0.93-0.99; p = 0.008), lower baseline NIHSS score (OR: 0.80; 95% CI: 0.73-0.89; p < 0.001), treatment with intravenous thrombolysis (OR: 3.06; 95% CI: 1.25-7.49; p = 0.014), lack of an undetermined aetiology (OR: 0.40; 95% CI: 0.16-0.998; p = 0.050), lack of pneumonia (OR: 0.08; 95% CI: 0.02-0.31; p < 0.001), and higher haemoglobin concentration on admission (OR: 1.31; 95% CI: 1.04-1.69; p = 0.024) were identified as predictors of 90-day GFO in this subgroup.
Conclusion: Almost half of patients with AIS in anterior circulation treated with mechanical thrombectomy experience DNI, which is a good predictor of 90-day GFO. Furthermore, 40% of patients without DNI achieve 90-day GFO which can be independently predicted by younger age, lower baseline NIHSS score, treatment with intravenous thrombolysis, higher haemoglobin concentration on admission, lack of undetermined ischaemic stroke aetiology, and lack of pneumonia.
Keywords: acute ischaemic stroke; delayed neurological improvement; early neurological improvement; mechanical thrombectomy.