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Long-term mortality after endovascular thrombectomy for stroke

  • Ulla Junttola
    Correspondence
    Corresponding author at: Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland.
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Departments of Neurology, Oulu University Hospital, OYS, P.O.BOX 21, Oulu 90029, Finland
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  • Author Footnotes
    1 These authors contributed equally to this work.
    Sanna Lahtinen
    Footnotes
    1 These authors contributed equally to this work.
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Anesthesiology and Intensive Care, Oulu, Finland
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  • Juha-Matti Isokangas
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Radiology, Oulu, Finland
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  • Author Footnotes
    1 These authors contributed equally to this work.
    Siiri Hietanen
    Footnotes
    1 These authors contributed equally to this work.
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Department of Internal Medicine and Cardiology, Central Ostrobothnian Central Hospital, Kokkola, Finland
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  • Merja Vakkala
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Anesthesiology and Intensive Care, Oulu, Finland
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  • Timo Kaakinen
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Anesthesiology and Intensive Care, Oulu, Finland
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  • Janne Liisanantti
    Affiliations
    Medical Research Center Oulu, Research Group of Surgery, Anesthesiology and Intensive Care, Finland

    Anesthesiology and Intensive Care, Oulu, Finland
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  • Author Footnotes
    1 These authors contributed equally to this work.
Open AccessPublished:October 15, 2022DOI:https://doi.org/10.1016/j.jstrokecerebrovasdis.2022.106832

      Abstract

      Objectives

      Endovascular thrombectomy (EVT) has become the standard treatment for large vessel occlusion (LVO) in acute ischemic stroke. Stroke trials typically report clinical outcome at the three-month time point but there is a lack of studies focusing on the long-term outcome after EVT.
      The aim of this study is to assess the long-term mortality after EVT for stroke and to determine the factors that are associated with mortality.

      Methods

      Retrospective single-center analysis of 323 patients who underwent EVT for stroke between the years 2015-2019 and survived at least 30 days. Patients were followed up until the end of the year 2020. Cox regression analysis was used to identify the factors associated with mortality.

      Results

      A total of 53 (16.4%) of the 30-day survivors died during the follow-up. According to the Cox regression analysis, mortality was associated with functional dependence (modified Rankin Scale (mRS) >2, HR 2.7 (95% CI 1.2-5.9), p=0.013), comorbidity (Charlson Comorbidity Index (CCI) ≥3, HR 2.7 (95% CI 1.4-5.5), p=0.004), stroke severity at baseline (National Institutes of Health Stroke Scale (NIHSS) >8, HR 1.9 (95% CI 1.1-3.3), p=0.026), and medical complications (HR 2.4 (95% CI 1.2-4.8), p=0.011). Procedural variables did not have an impact on mortality.

      Conclusions

      Functional dependence, stroke severity, comorbidity, and medical complications during the hospital stay were associated with the long-term mortality after EVT for stroke.

      Introduction

      Hyperacute treatments for acute ischemic stroke (AIS) have evolved in the recent years as endovascular thrombectomy (EVT) has become well established standard treatment in large vessel occlusion (LVO)
      • Berkhemer O.A.
      • Fransen P.S.S.
      • Beumer D.
      • et al.
      A randomized trial of intraarterial treatment for acute ischemic stroke.
      • Saver J.L.
      • Goyal M.
      • Bonafe A.
      • et al.
      Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke.
      • Jovin T.G.
      • Chamorro A.
      • Cobo E.
      • et al.
      Thrombectomy within 8 hours after symptom onset in ischemic stroke.
      • Goyal M.
      • Demchuk A.M.
      • Menon B.K.
      • et al.
      Randomized assessment of rapid endovascular treatment of ischemic stroke.
      • Campbell B.C.V.
      • Mitchell P.J.
      • Kleinig T.J.
      • et al.
      Endovascular therapy for ischemic stroke with perfusion-imaging selection.
      • Albers G.W.
      • Marks M.P.
      • Kemp S.
      • et al.
      Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging.
      • Nogueira R.G.
      • Jadhav A.P.
      • Haussen D.C.
      • et al.
      Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct.
      and the treatment of distal medium vessel occlusions with EVT is emerging.
      • Saver J.L.
      • Chapot R.
      • Agid R.
      • et al.
      Thrombectomy for distal, medium vessel occlusions.
      Despite the advances in the acute stroke treatments, stroke is still the second leading cause of death globally.
      • Abbafati C.
      • Abbas K.M.
      • Abbasi-Kangevari M.
      • et al.
      Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019.
      Life expectancy is increasing worldwide and the incidence of stroke is greatly influenced by age.
      • Béjot Y.
      • Bailly H.
      • Durier J.
      • Giroud M.
      Epidemiology of stroke in Europe and trends for the 21st century.
      Hence, the total number of strokes is evidently expected to increase in coming years. The benefit of EVT is confirmed also in patients older than 80 years
      • Goyal M.
      • Menon B.K.
      • van Zwam W.H.
      • et al.
      Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials.
      thus it is not appropriate to exclude elderly patients from the intervention solely based on age. For cost-effective utilization of healthcare resources, the recognition of patients who will benefit from acute stroke interventions becomes essential. There is a need to identify factors which are associated with poor outcome and mortality after EVT to improve patient selection and to prevent futile treatment.
      Outcomes after EVT are typically reported at standard 90-day time point. However, stroke patients often have comorbidities
      • Noor A.
      • Bennett G.
      • Arndt S.
      • Vidal G.
      Comorbidities related to clinical outcomes in patients with acute ischemic stroke undergoing mechanical thrombectomy: review of literature and experience at a single comprehensive stroke center.
      and suffer from disability.
      • Wafa H.A.
      • Wolfe C.D.A.
      • Emmett E.
      • Roth G.A.
      • Johnson C.O.
      • Wang Y.
      Burden of Stroke in Europe: thirty-year projections of incidence, prevalence, deaths, and disability-adjusted life years.
      Patients undergoing EVT are also prone to medical complications which are strongly associated with comorbidity and mortality in short-term follow-up.
      • Junttola U.
      • Lahtinen S.
      • Liisanantti J.
      • Vakkala M.
      • Kaakinen T.
      • Isokangas J.M.
      Medical complications and outcome after endovascular therapy for acute ischemic stroke.
      The data regarding long-term survival after EVT is limited, although a few studies suggest that the benefits on functional outcome are sustained and similar to 90-day outcome.
      • McCarthy D.J.
      • Diaz A.
      • Sheinberg D.L.
      • et al.
      Long-term outcomes of mechanical thrombectomy for stroke: a meta-analysis.
      • Dávalos A.
      • Cobo E.
      • Molina C.A.
      • et al.
      Safety and efficacy of thrombectomy in acute ischaemic stroke (REVASCAT): 1-year follow-up of a randomised open-label trial.
      • van den Berg L.A.
      • Dijkgraaf M.G.W.
      • Berkhemer O.A.
      • et al.
      Two-year outcome after endovascular treatment for acute ischemic stroke.
      We aimed to investigate the long-term mortality after EVT for stroke and to determine the factors which are associated with mortality.

      Material and methods

      This retrospective study was conducted at Oulu University Hospital, Finland, the Comprehensive Stroke Center for the four Primary Stroke Centers in Northern Finland. The study protocol was approved by the hospital administration (reference number 268/2019) and due to the retrospective study design no statement from the local ethics committee was needed.

      Patients and inclusion criteria

      During the time period between January 2015 and December 2019, 380 consecutive patients received EVT for acute stroke at Oulu University Hospital. In our hospital patients are eligible for EVT when they present with acute ischemic stroke due to an occlusion in the intracranial internal carotid artery, the first or second segment of the middle cerebral artery or in the basilar artery established on computed tomographic angiography (CTA) and a score of 6 or higher on the National Institutes of Health Stroke Scale (NIHSS) and no large ischemic lesion on baseline non-contrast head computed tomography (CT). In extended time-window patient selection is based on perfusion imaging. These patients were retrospectively identified and screened from the Thrombectomy Registry of Oulu University Hospital. A total of 323 patients who survived at least 30 days after intervention were included into the present study.
      We collected patients` baseline demographics and characteristics including age, sex, National Institutes of Health Stroke Scale (NIHSS) score on admission, pre-stroke modified Rankin scale (mRS) score, and Charlson Comorbidity Index (CCI). CCI is a method which categorizes patient`s comorbidities based on the diagnoses in medical records.
      • Deyo R.A.
      • Cherkin D.C.
      • Ciol M.A.
      Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases.
      Procedural data included treatment with intravenous thrombolysis and the type of stroke onset. We used the determination of occlusion site as either anterior or posterior circulation. The grade of recanalization was defined as modified Thrombolysis in Cerebral Infarction Scale (mTICI).
      • Tung E.L.
      • McTaggart R.A.
      • Baird G.L.
      • et al.
      Rethinking thrombolysis in cerebral Infarction 2b: which thrombolysis in cerebral infarction scales best define near complete recanalization in the modern thrombectomy era?.
      Post-procedural variables included NIHSS score on the first post-procedural day, infarction size in 24 h control head computed tomography (CT), and medical complications during the hospital stay. Laboratory results during the first three days of the hospital stay were collected and the hospital LOS was determined. The data was collected on structured forms and digitalized.
      Complications were classified as reported in our previous study which focused on medical complications in this patient group
      • Junttola U.
      • Lahtinen S.
      • Liisanantti J.
      • Vakkala M.
      • Kaakinen T.
      • Isokangas J.M.
      Medical complications and outcome after endovascular therapy for acute ischemic stroke.
      including medical complications (pneumonia, acute myocardial infarction, acute kidney injury, cardiac insufficiency, pulmonary embolism, deep venous thrombosis, delirium, gastrointestinal bleeding and atrial fibrillation) and neurological complications (any hemorrhagic findings in control head CT and acute seizures).
      Statistics Finland provided the data concerning the dates of death. Patients were followed until the end of the year 2020.

      Statistical analysis

      The data was analyzed using IBM SPSS Statistics for Windows (Version 27 IBM Corp). Categorical variables, presented as numbers and percentages, were compared using Pearson`s Chi square test. Continuous variables, presented as medians and 25th and 75th percentiles [25th–75th PCT], were analyzed using the non-parametric Mann-Whitney test. P-value less than 0.05 was considered statistically significant. Variables with univariate significance less than 0.1 were entered into a multivariate proportional hazards Cox model to assess hazard ratios (HR) and 95% confidence intervals (95% CI) for mortality. Variables with multivariate significance less than 0.05, and those with significant impact on the log likelihood function were kept in the model. According to the Cox regression model, Kaplan-Meier survival curves were drawn for the clinically most significant variables.

      Results

      During the study period 379 patients underwent EVT. One patient experienced two separate interventions due to a recurrent stroke during two hospital admissions. During the hospital stay 18 (4.8%) patients died. At 30 days, there were 323 (85.2%) patients alive. The median age of these 30-day survivors was 70 [60-79] years and 177 (54.8%) of them were male. (Table 1).
      Table 1Baseline characteristics of 30-day survivors after endovascular thrombectomy for stroke.
      AliveDeceasedMissingP-Value
      N=270N=53
      Gender, male154 (57.0)23 (43.4)00.068
      Age, yr69 [58-77]78 [69-84]0<0.001
      Weight, kg80 [67-86]75 [67-84]320.220
      Smoking54(20.0)3 (5.7)00.012
      CCI-score >3
      Charlson Comorbidity Index
      129 (48.0)41 (77.4)1<0.001
      mRS baseline
      modified Rankin Scale of functional dependence ranges from 0 (no symptoms) to 6 (death)
      0 [0-1]1 [0-2]3<0.001
      NIHSS baseline
      National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      13 [7-16]15 [11-18]00.008
      Laboratory Results
      Hemoglobin g/L136 [126-148]130 [118-142]40.019
      Thrombocytes20.514
      E9/L216 [178-252]225 [170-270]
      Creatinine40.202
      μmol/L72 [59-85]77 [59-90]
      CRP mg/L
      C-reactive protein
      0 [0-7]9 [0-20]0<0.001
      Categorical variables are presented as absolute numbers (N) and percentages (%). Continuous variables are presented as medians with 25th and 75th percentiles [25-75th PCT].
      Charlson Comorbidity Index
      modified Rankin Scale of functional dependence ranges from 0 (no symptoms) to 6 (death)
      § National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      C-reactive protein
      The median follow-up time was 2.9 [1.9-4.1] years and 53 (16.4%) of the 30-day survivors died during the follow-up. The mortality of the 30-day survivors was 3.1% at 90 days and 9.0% at one year. Patient baseline characteristics are shown in Table 1. The non-survivors were older (78 [69-84] vs 69 [58-77] years, p<0.001), had higher CCI-score (6 [4-7] vs 3 [2-5], p<0.001), lower pre-stroke functional status (1 [0-2] vs [0-1] mRS, p<0.001), and higher CRP (9 [0-20] vs 0 [0-7], p<0.001) compared with the survivors.
      There were no differences in procedural variables between the non-survivors and the survivors. The rate of complete recanalization was comparable in both groups (54.3% vs 61.3%, p=0.376) as was also the rate of posterior circulation stroke (15.1% vs 18.7%). (Table 2).
      Table 2Procedural data of 30-day survivors after endovascular thrombectomy for stroke.
      AliveDeceasedMissingP-value
      N=270N=53
      Treatment with intravenous thrombolysis
      IVT
      Intravenous thrombolysis
      +EVT
      Endovascular thrombectomy
      138 (51.5)25 (47.2)20.565
      EVT alone
      Endovascular thrombectomy
      130 (48.5)28 (52.8)
      Type of stroke onset
      Witnessed209 (78.6)44 (83.0)40.694
      Unwitnessed57 (21.4)9 (17.0)
      Occlusion site
      Anterior circulation217 (81.3)45 (84.9)30.531
      Posterior circulation50 (18.7)8 (15.1)
      Recanalization result
      The modified Thrombolysis in Cerebral Infarction scale, ranges from 0 to 3, with a grade of 2b, 2c and 3 indicating successful reperfusion
      TICI 3149 (61.3)25 (54.3)
      TICI 2B-2C83 (34.2)17 (36.9)340.429
      TICI 0-2A11 (4.5)4 (8.6)
      Process measures
      Median time from stroke onset to groin puncture (min)309 [210-516]314 [235-488]00.556
      Median time from hospital admission to groin puncture (min)74 [44-114]81 [55-128]00.165
      Median time from groin puncture to recanalization (min)45 [29-70]50 [28-84]00.369
      Contrast media amount (ml)170 [140-205]170 [135-200]00.881
      Categorical variables are presented as absolute numbers (N) and percentages (%). Continuous variables are presented as medians with 25th and 75th percentiles [25–75th PCT].
      Intravenous thrombolysis
      Endovascular thrombectomy
      § The modified Thrombolysis in Cerebral Infarction scale, ranges from 0 to 3, with a grade of 2b, 2c and 3 indicating successful reperfusion
      The non-survivors had higher NIHSS-score (12 [4-16] vs 6 [4-13] p=0.009) on the first post-procedural day. They also had lower albumin levels (30 [26-33] vs 32 [29-34], p=0.008) and suffered more often medical complications (77.4% vs 53.7%), p=0.001) compared with the survivors. Hemorrhagic transformation in control neuroimaging was more common among the non-survivors, but the difference was not statistically significant (26.4% vs 18.7%, p= 0.196). The size of the infarction was larger in the non-survivors (p=0.036) (Table 3). The rate of the symptomatic intracranial hemorrhage among the 30-day survivors was 5.4%.
      Table 3Post-procedural outcome of 30-day survivors after endovascular thrombectomy for stroke.
      AliveDeceasedMissingP-Value
      N=270N=53
      Clinical
      Median NIHSS
      score on 1st post-
      procedural day
      National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      6 [4-13]12 [4-16]00.009
      Control Imaging
      Infarction size
      No infarction35 (13.0)11 (20.7)
      Small-medium infarction142 (53.0)18 (34.0)
      Large infarction91 (34.0)24 (45.3)20.036
      Hemorrhage
      No hemorrhage218 (81.3)39 (73.6)
      Any hemorrhage50 (18.7)14 (26.4)0.196
      Medical complications
      No125 (46.3)12 (22.6)
      Yes145 (53.7)41 (77.4)00.001
      Neurological complications
      No224 (83.0)39 (73.6)
      Yes46 (17.0)14 (26.4)00.108
      Laboratory results
      Creatinine μmol/L65 [55-78]72 [58-85]470.059
      Albumin g/L32 [29-34]30 [26-33]1130.008
      Hosp LOS (d)
      Hospital length of stay
      6 [4-8]6 [4-8]00.916
      Categorical variables are presented as numbers (N) and percentages (%). Continuous variables are presented as medians with 25th and 75th percentiles [25–75th PCT].
      National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      Hospital length of stay
      According to the Cox regression analysis pre-stroke functional dependence (mRS >2, HR 2.7 (95% CI 1.2-5.9), p=0.013), medical complications (HR 2.4 (95% CI 1.2-4.8), p=0.011), stroke severity at baseline (NIHSS >8, HR 1.9 (95% CI 1.1-3.3), p=0.026), and comorbidity (CCI≥3, HR 2.7 (95% CI 1.4-5.5), p=0.004) were associated with death during the follow-up (Table 4).
      Table 4HR and 95% confidence intervals for death among 30-day survivors after endovascular thrombectomy for stroke.
      HR (95% CI)P-value
      mRS >2
      modified Rankin Scale of functional dependence ranges from 0 (no symptoms) to 6 (death)
      2.7 (1.2-5.9)0.013
      At least moderate dependence
      At least one medical complication2.4 (1.2-4.8)0.011
      NIHSS baseline >8
      National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      1.9 (1.1-3.3)0.026
      CCI ≥3
      Charlson Comorbidity Index
      2.7 (1.4-5.5)0.004
      modified Rankin Scale of functional dependence ranges from 0 (no symptoms) to 6 (death)
      National Institutes of Health Stroke Scale range from 0 to 42, with higher scores indicating a greater clinical deficit
      § Charlson Comorbidity Index
      The cumulative survival of the patients with medical complications compared with the patients with no medical complications is presented in Fig. 1. The cumulative survival in comparison between the patients with high and low comorbidity burden is presented in Fig. 2.
      Fig 1
      Fig. 1Kaplan-Meier curve for long-term cumulative survival in the 30-day survivors with and without medical complications in 3-year follow-up.
      Fig 2
      Fig. 2Kaplan-Meier curve for long-term cumulative survival in the 30-day survivors with either high or low comorbidity burden in 3-year follow-up.

      Discussion

      Our study shows that after surviving the acute phase, a total of 16% of patients who underwent EVT for stroke died during the long-term follow-up. Pre-stroke functional dependence, comorbidity, stroke severity, and medical complications during the hospital stay were independently associated with mortality. There was no difference in recanalization result, hemorrhagic transformation, or posterior circulation stroke between the survivors and the non-survivors.
      In the present study, the mortality among 30-day survivors was lower compared with previous anterior circulation EVT studies; REVASCAT and MR CLEAN reported 23% mortality at one year and 26.0% cumulative mortality in two-year follow-up, respectively.
      • Dávalos A.
      • Cobo E.
      • Molina C.A.
      • et al.
      Safety and efficacy of thrombectomy in acute ischaemic stroke (REVASCAT): 1-year follow-up of a randomised open-label trial.
      ,
      • van den Berg L.A.
      • Dijkgraaf M.G.W.
      • Berkhemer O.A.
      • et al.
      Two-year outcome after endovascular treatment for acute ischemic stroke.
      Accordingly, Chinese study reported a mortality rate of 28% in a median follow-up period of 20 months.
      • Zhao W.
      • Shang S.
      • Li C.
      • et al.
      Long-term outcomes of acute ischemic stroke patients treated with endovascular thrombectomy: a real-world experience.
      Comparably Wu et al reported a rate of 38% for one-year mortality in basilar artery occlusion patients treated with EVT.
      • Wu L.
      • Zhang D.
      • Chen J.
      • et al.
      Long-term outcome of endovascular therapy for acute basilar artery occlusion.
      Our study population represents real-world clinical environment since we are the only operating Comprehensive Stroke Center in Northern Finland. We included all consecutive EVT-patients in this study and our study population contains both anterior and posterior circulation occlusions. Interestingly, our data suggests that posterior circulation occlusion does not have an impact on long-term mortality, even though short-term mortality in posterior circulation stroke is rather high.
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      • et al.
      Predicting early mortality of acute ischemic stroke: score-based approach.
      Although data regarding prognostic factors for long-term survival after EVT are limited, other studies have previously identified that stroke severity,
      • Zhao W.
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      Long-term outcomes of acute ischemic stroke patients treated with endovascular thrombectomy: a real-world experience.
      ,
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      Identifying patients at high risk for poor outcome after intra-arterial therapy for acute ischemic stroke.
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      Stroke prognostication using age and NIH stroke scale: SPAN-100.
      comorbidity,
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      Predicting long-term outcome after endovascular stroke treatment: the totaled health risks in vascular events score.
      and pre-stroke functional dependence
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      Clinical outcome after thrombectomy in patients with stroke with premorbid modified rankin scale scores of 3 and 4: a cohort study with 136 patients.
      ,
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      • et al.
      Stroke patients treated by thrombectomy in real life differ from cohorts of the clinical trials: a prospective observational study.
      are associated with poor outcome. Our study presents a novel finding of these variables being independently associated with the long-term mortality in EVT-patients. According to the present results, after the primary survival from the stroke, the patient-related factors instead of the stroke-related factors play a major role in the survival. According to our knowledge, medical complications have not previously been reported to be related to the long-term mortality in this patient group. We have recently shown that the medical complications are common after EVT and have a negative impact on the short-term functional outcome.
      • Junttola U.
      • Lahtinen S.
      • Liisanantti J.
      • Vakkala M.
      • Kaakinen T.
      • Isokangas J.M.
      Medical complications and outcome after endovascular therapy for acute ischemic stroke.
      Patients with comorbidities are prone to medical complications.
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      • Lee J.
      • Sohn M.K.
      • et al.
      Risk factors and functional impact of medical complications in stroke.
      According to these findings, medical complications are not directly related to unfavorable outcomes; they are rather a surrogate of poor health leading to death during the recovery phase of acute disease. Among surgical patients, postoperative complications which occurred during the first 30 postoperative days are more significantly related to survival than operative risk or perioperative risk factors.
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      Short- and long-term mortality and causes of death after reconstruction of cancers of the head and neck with free flaps.
      Our finding that medical complications are associated with long-term mortality suggests the same and indicates that medical complications have a sustained negative impact on the survival after invasive treatments.
      Functionally dependent patients have been excluded from randomized trials of acute stroke treatments
      • Berkhemer O.A.
      • Fransen P.S.S.
      • Beumer D.
      • et al.
      A randomized trial of intraarterial treatment for acute ischemic stroke.
      • Saver J.L.
      • Goyal M.
      • Bonafe A.
      • et al.
      Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke.
      • Jovin T.G.
      • Chamorro A.
      • Cobo E.
      • et al.
      Thrombectomy within 8 hours after symptom onset in ischemic stroke.
      • Goyal M.
      • Demchuk A.M.
      • Menon B.K.
      • et al.
      Randomized assessment of rapid endovascular treatment of ischemic stroke.
      • Campbell B.C.V.
      • Mitchell P.J.
      • Kleinig T.J.
      • et al.
      Endovascular therapy for ischemic stroke with perfusion-imaging selection.
      and there is uncertainty if they could benefit from the intervention. Despite conflicting results concerning possible benefits of acute treatments in this patient group,
      • Gumbinger C.
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      • Ippen F.
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      Outcomes of patients with stroke treated with thrombolysis according to prestroke Rankin Scale scores.
      ,
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      Safety and outcome of endovascular treatment in prestroke-dependent patients: results from MR CLEAN registry.
      our study shows that pre-stroke dependency has an independent association with mortality. Similarly, Swedish group reported a clear association between pre-stroke functional dependency and high mortality rate in a long-term follow-up after acute ischemic stroke.
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      The current knowledge suggests withholding EVT or at least making treatment decisions upon individual basis in this patient group. However, in the every-day clinical practice time-sensitive assessments of patient´s functional capacity may be complex and not always precise.
      According to previous studies, successful recanalization has been associated with favorable outcome
      • Deb-Chatterji M.
      • Pinnschmidt H.
      • Flottmann F.
      • et al.
      Stroke patients treated by thrombectomy in real life differ from cohorts of the clinical trials: a prospective observational study.
      ,
      • Fields J.D.
      • Lutsep H.L.
      • Smith W.S.
      Higher degrees of recanalization after mechanical thrombectomy for acute stroke are associated with improved outcome and decreased mortality: pooled analysis of the MERCI and multi MERCI trials.
      and decreased likelihood of death.
      • Fields J.D.
      • Lutsep H.L.
      • Smith W.S.
      Higher degrees of recanalization after mechanical thrombectomy for acute stroke are associated with improved outcome and decreased mortality: pooled analysis of the MERCI and multi MERCI trials.
      ,
      • Awad A.W.
      • Kilburg C.
      • Ravindra V.M.
      • et al.
      Predicting death after thrombectomy in the treatment of acute stroke.
      In contrast to previous results, we did not find an association between recanalization result and mortality. This difference may be explained by the fact that previous studies have focused on the short-term outcome and survival. It may be hypothesized that there are different factors impacting the short- and long-term mortalities. Moreover, we serve as Comprehensive Stroke Center and approximately 40% of our patients are transferred from other hospitals. Transfer delay contributes to expansion of neuronal injury and reduces the impact of successful recanalization.

      Clinical significance

      The benefits of EVT are confirmed in wide range of patients
      • Goyal M.
      • Menon B.K.
      • van Zwam W.H.
      • et al.
      Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials.
      and in extended time-window.
      • Albers G.W.
      • Marks M.P.
      • Kemp S.
      • et al.
      Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging.
      ,
      • Nogueira R.G.
      • Jadhav A.P.
      • Haussen D.C.
      • et al.
      Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct.
      Increasing amount of acute stroke patients are being evaluated to meet eligibility for acute stroke treatments, including thrombectomy. Despite promising results there are still patients who remain severely disabled or die after acute interventions.
      • Ramos L.A.
      • Kappelhof M.
      • van Os H.J.A.
      • et al.
      Predicting poor outcome before endovascular treatment in patients with acute ischemic stroke.
      ,
      • Karamchandani R.R.
      • Rhoten J.B.
      • Strong D.
      • Chang B.
      • Asimos A.W.
      Mortality after large artery occlusion acute ischemic stroke.
      Appropriate patient selection is essential for optimal and cost-effective utilization of limited health care resources. Identifying factors which are associated with mortality provide tools for stroke clinicians for the every-day decision making.
      Comorbidity and functional dependence have a close relationship.
      • Wolff J.L.
      • Boult C.
      • Boyd C.
      • Anderson G.
      Newly reported chronic conditions and onset of functional dependency.
      According to our results, these factors should be assessed when acute stroke patients are being evaluated to meet eligibility for EVT to prevent futile recanalization. Furthermore, every attempt should be made to prevent medical complications in this patient group.
      We defined stroke severity as high baseline NIHSS similarly to many previous studies.
      • Zhao W.
      • Shang S.
      • Li C.
      • et al.
      Long-term outcomes of acute ischemic stroke patients treated with endovascular thrombectomy: a real-world experience.
      ,
      • Wu L.
      • Zhang D.
      • Chen J.
      • et al.
      Long-term outcome of endovascular therapy for acute basilar artery occlusion.
      ,
      • Awad A.W.
      • Kilburg C.
      • Ravindra V.M.
      • et al.
      Predicting death after thrombectomy in the treatment of acute stroke.
      ,
      • Karamchandani R.R.
      • Rhoten J.B.
      • Strong D.
      • Chang B.
      • Asimos A.W.
      Mortality after large artery occlusion acute ischemic stroke.
      Although we found baseline NIHSS to have an independent association with long-term mortality, it alone possesses an incomplete ability to predict outcome. Beyond admission, there are several additive factors having an impact on outcome. Baseline NIHSS is a good clinical tool but should not be used alone in the decision making when selecting patients for the intervention.

      Limitations

      The present study has some limitations. First, low number of patients can be considered as a limitation but increasing the number of patients would have expanded the time period remarkably. On the other hand, we are the only operating Comprehensive Stroke Center in Northern Finland and therefore this is a population-based study. Although we used CCI to measure comorbidities precisely, we did not estimate the prognostic effects of individual comorbid conditions. Different comorbid conditions have unequal effects on mortality and survival, which should be kept in mind when making treatment decisions on the basis of comorbidity. Additionally, we were not able to provide ASPECTS on imaging at baseline because it is not commonly used score in our hospital. Furthermore, we did not explore the causes of death and are not able to determine if there were preventable or avoidable factors affecting mortality. The retrospective study setting is also a limitation since there might be factors which cannot have been observed and reported and might still have an impact on the survival. However, due to retrospective design the study protocol itself has not interfered in the treatment decisions or evaluation of treatment results. Thus, the study depicts reliably the real-life course of EVT for acute ischemic stroke.

      Conclusion

      According to the present results, the 30-day survivors of acute ischemic stroke treated with EVT have relatively good prognosis in the long-term follow-up. Comorbidity, functional dependency, stroke severity, and medical complications during the hospital stay were independently associated with the long-term mortality after EVT for stroke. These factors should be considered when evaluating stroke patients to meet eligibility for acute stroke interventions.

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