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Ischemic Stroke
Original research
Need for rescue treatment and its implication: stent retriever versus contact aspiration thrombectomy
  1. Dong-Hun Kang1,
  2. Jin Woo Kim2,
  3. Byung Moon Kim3,
  4. Ji Hoe Heo4,
  5. Hyo Suk Nam4,
  6. Young Dae Kim4,
  7. Yang-Ha Hwang5,
  8. Yong-Won Kim5,
  9. Jang-Hyun Baek6,
  10. Joonsang Yoo7,
  11. Dong Joon Kim3,
  12. Pyoung Jeon8,
  13. Oh Young Bang9,
  14. Seung Kug Baik10,
  15. Sang Hyun Suh11,
  16. Kyung-Yul Lee12,
  17. Hyo Sung Kwak13,
  18. Hong Gee Roh14,
  19. Young-Jun Lee15,
  20. Sang Heum Kim16,
  21. Chang-Woo Ryu17,
  22. Yon-Kwon Ihn18,
  23. Byungjun Kim19,
  24. Hong Jun Jeon20,
  25. Jun Soo Byun21,
  26. Sangil Suh22,
  27. Jeong Jin Park23,
  28. Jieun Roh10
  1. 1 Department of Neurosurgery and Radiology, Kyungpook National University Hospital, School of Medicine, Kyungpook National University, Daegu, South Korea
  2. 2 Department of Radiology, Inje University Ilsan Paik Hospital, Goyang, South Korea
  3. 3 Department of Radiology, Severance stroke center, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
  4. 4 Department of Neurology, Severance stroke center, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
  5. 5 Department of Neurology, Kyungpook National University Hospital, School of Medicine, Kyungpook National University, Daegu, South Korea
  6. 6 Department of Neurology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea
  7. 7 Department of Neurology, Keimyung University School of Medicine, Daegu, South Korea
  8. 8 Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
  9. 9 Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
  10. 10 Department of Radiology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, South Korea
  11. 11 Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
  12. 12 Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
  13. 13 Department of Radiology, Chonbuk National University Medical School and Hospital, Jeonju, South Korea
  14. 14 Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, South Korea
  15. 15 Department of Radiology, Hanyang University College of Medicine and Hospital, Seoul, South Korea
  16. 16 Department of Radiology, CHA Bundang Medical Center, CHA University, Seongnam, South Korea
  17. 17 Department of Radiology, Kyung Hee University Hospital at Gangdong, School of Medicine, Kyung Hee University, Seoul, South Korea
  18. 18 Department of Radiology, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Suwon, South Korea
  19. 19 Department of Radiology, Korea University Anam Hospital, Seoul, South Korea
  20. 20 Department of Neurosurgery, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, South Korea
  21. 21 Department of Radiology, Chung-Ang University Hospital, Seoul, South Korea
  22. 22 Department of Radiology, Korea University College of Medicine, Guro Hospital, Seoul, South Korea
  23. 23 Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, South Korea
  1. Correspondence to Prof Byung Moon Kim, Department of Radiology, Severance stroke center, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea; bmoon21{at}hanmail.net

Abstract

Backgroud The need for rescue treatment (RT) may differ depending on first-line modality (stent retriever (SR) or contact aspiration (CA)) in endovascular thrombectomy (EVT). We aimed to investigate whether the type of first-line modality in EVT was associated with the need for RT.

Methods We identified all patients who underwent EVT for anterior circulation large-vessel occlusion from prospectively maintained registries of 17 stroke centers. Patients were dichotomized into SR-first and CA-first. RT involved switching to the other device, balloon angioplasty, permanent stenting, thrombolytics, glycoprotein IIb/IIIa antagonist, or any combination of these. We compared clinical characteristics, procedural details, and final recanalization rate between the two groups and assessed whether first-line modality type was associated with RT requirement and if this affected clinical outcome.

Results A total of 955 patients underwent EVT using either SR-first (n=526) or CA-first (n=429). No difference occurred in the final recanalization rate between SR-first (82.1%) and CA-first (80.2%). However, recanalization with the first-line modality alone and first-pass recanalization rates were significantly higher in SR-first than in CA-first. CA-first had more device passes and higher RT rate. The RT group had significantly longer puncture-to-recanalization time (93±48 min versus 53±28 min). After adjustment, CA-first remained associated with RT (OR, 1.367; 95% CI, 1.019 to 1.834). RT was negatively associated with good outcome (OR, 0.597; 95% CI, 0.410 to 0.870).

Conclusion CA was associated with requiring RT, while recanalization with first-line modality alone and first-pass recanalization rates were higher with SR. RT was negatively associated with good outcome.

  • acute stroke
  • thrombectomy
  • rescue treatment

https://doi.org/10.1136/neurintsurg-2018-014696

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    Introduction

    In the era of endovascular thrombectomy (EVT) for acute stroke, the two main modalities used are stent retriever (SR) and contact aspiration (CA).1–3 Although a recent randomized clinical trial showed no difference in the final recanalization rate and clinical outcome,2 differences that exist in procedural details and outcomes between the two modalities have not been clarified.3 4 Furthermore, because the two EVT techniques are quite different in mode of action and procedural detail,5–11 it seems that a major determinant in which is applied as the first-line modality is the experiences and preference of operators. In other words, there can be a difference in procedural outcome not only by the EVT modality itself but also by an operator’s experience. Because recanalization is one of the important factors for a good outcome,12 13 rescue treatment (RT) is often required after the failure of the first-line modality.14–18 However, if recanalization can be achieved by the first-line modality without RT, it would be better than if recanalization was obtained by RT after the failure of the first-line modality.6 19

    We hypothesized there would be a difference in the need for RT between CA and SR first-line modality to achieve recanalization success. We tested whether the type of first-line modality was associated with the need for RT in a large cohort of patients.

    Methods

    The data that support the findings of this study are available from the corresponding author on reasonable request.

    The Institutional Review Board of every participating hospital approved this study and waived the requirement for informed consent for study inclusion based on the retrospective study design.

    Patient enrollment

    We identified consecutive patients who underwent EVT using either SR or CA as the first-line modality for acute ischemic stroke due to relevant intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) M1 or proximal M2 segment and had functional outcome (defined by modified Rankin Scale, mRS, score 0–6) at 3 months from the prospectively maintained registries of 17 comprehensive stroke centers between January 2011 and December 2015. Enrollment criteria for entry into the analysis were as follows: (1) age ≥18 years, (2) initial National Institute of Health Stroke Scale (NIHSS) score ≥4, (3) onset-to-puncture time (OPT) ≤600 min, (4) mRS before the qualifying stroke of 0 or 1, (5) recanalization success assessable on catheter angiogram, and (6) documented intracranial ICA or MCA M1 or proximal M2 occlusion on CT, MR, or catheter angiography. Tandem atherosclerotic or dissecting cervical ICA occlusion accompanied by intracranial LVO was included. Multifocal LVO (bilateral anterior or involvement of both anterior and posterior circulations) was excluded.

    Endovascular thrombectomy procedure

    For patients eligible for intravenous tissue plasminogen activator (tPA) treatment, the full dose of tPA (0.9 mg/kg) was administered. All EVT procedures were performed under local anesthesia with or without conscious sedation. A 6 F shuttle sheath (Cook, Indianapolis, IN, USA) or an 8- to 9 F balloon guide catheter (BGC; Cello, Covidien, Irvine, CA, USA or Optimo, Tokai Medical Products, Aichi, Japan) was used as a guide catheter. The use of a BGC depended on the protocol of each participating site. When a BGC was used, the balloon was inflated and then either SR or CA was conducted under constant aspiration of the BGC with a 20 mL or 50 mL syringe during the retrieval. Two types of stent retrievers (Solitaire AB/FR, ev3 Irvine, CA, USA or Trevo Proview, Stryker, CA, USA) were used for SR thrombectomy and the Penumbra System (Penumbra, Alameda, CA, USA) was used predominantly for CA thrombectomy. The choice of first-line modality (SR or CA) and the number of attempts of first-line modality depended on the protocol of each participating site and the preference of primary operators. After first-line modality failure, the operator determined whether to conduct RT or to abandon a further EVT attempt after taking into consideration the assumptive occlusion pathomechanism, the patient’s clinical condition, and other relevant factors. RT consisted of switching modality (change of the first-line modality to the other modality or the simultaneous use of both), balloon angioplasty, permanent stenting, intraarterial thrombolytics, intraarterial glycoprotein IIb/IIIa antagonist, or any combination of these.

    Data collection and assessment

    All data, including clinical, laboratory findings and procedural details, were obtained from the prospectively maintained registries for acute stroke in each participating hospital and then entered into a pre-defined case report form (CRF). The CRFs were anonymized and then sent to a central core laboratory. All imaging data including pre-treatment non-enhanced CT (NECT) with CTA and/or diffusion-weighted magnetic resonance imaging (MRI) with MRA, catheter angiograms during the EVT, and follow-up CT or MRI were anonymized and sent to the central core laboratory as digital imaging and communication in medicine (DICOM) files. Two neuroradiologists independently assessed the images for Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and two interventional neuroradiologists independently assessed whether recanalization success was achieved on the catheter angiograms during the EVT. The reviewers were blind to the clinical outcome. Recanalization success was defined as modified Thrombolysis In Cerebral Ischemia (mTICI) grade 2b or 3 on the final control angiogram. Discrepant cases were resolved by consensus between raters who were still blind to both the clinical outcome and the findings on follow-up CT or magnetic resonance (MR) imaging.

    Outcome measurement

    The rates of recanalization success and good functional outcome were evaluated in all patients who fulfilled the enrollment criteria. A good outcome was defined as a mRS of 0–2 at 3 months. The patients were dichotomized into SR-first or CA-first according to which was the first-line modality for EVT. We compared the two groups by clinical characteristics; procedural details, including the number of device passes; the final recanalization success rate; onset-to-puncture time; puncture-to-recanalization time in cases where recanalization was successful; and good outcome rate. Finally, we tested whether the type of first-line modality was associated with the need for RT.

    Statistical analysis

    All statistical analyses were performed using IBM SPSS Statistics version 23 (IBM Corp., Armonk, NY, USA). All categorical variables were presented as a number and frequency (%) and continuous variables were presented as a mean ±SD In the univariate analysis, χ2 test, Fisher’s exact test, Student’s t-test, and Mann–Whitney U test were used to compare SR-first and CA-first groups in clinical variables and procedural details. We also compared patients with and without RT using the same variables. Finally, multivariate binary logistic regression analysis was performed to test whether the type of first-line modality was independently associated with RT and whether RT affected clinical outcome. We included all variables that showed potential association in the univariate analysis (P<0.20) in the binary logistic regression analysis. We assessed the model’s goodness of fit with the Hosmer and Lemeshow test.

    A P-value of less than 0.05 was considered significant. For multivariate analyses, OR is presented with a 95% CI.

    Results

    A total of 955 patients underwent EVT using either SR-first (n=526; age, 67. 2±12.5 years; M:F=55.5:44.5) or CA-first (n=429; 68.4±11.4 years; M:F=50.1:49.9). In CA-first patients BGC was used less frequently, onset-to-puncture and puncture-to-recanalization times were shorter, there were more device passes and a higher RT rate. There was no difference in final recanalization rate between SR-first (82.1%) and CA-first (80.2%) groups. However, the rates of recanalization with the first-line modality alone (SR-first, 65.0% versus CA-first, 55.9%; P=0.005) (figure 1) and first-pass recanalization (SR-first, 35.6% versus CA-first, 15.4%; P<0.001) were significantly higher in the SR-first than in the CA-first group (table 1). Patients with RT had higher rates of diabetes, smoking, distal ICA involvement, CA-first, and longer puncture-to-recanalization time, while lower rates of atrial fibrillation, BGC use, and good outcome (table 2). In the binary logistic regression analysis, CA-first patients (OR, 1.367; 95% CI, 1.019 to 1.834) remained independently associated with requiring RT, along with diabetes, smoking, atrial fibrillation, intravenous tPA administration, distal ICA involvement, and use of a BGC (table 3). RT requirement was independently and negatively associated with a good outcome (OR, 0.597; 95% CI, 0.410 to 0.870) (table 4).

    Figure 1
    Figure 1

    Flowchart of stepwise endovascular treatment for large vessel occlusion with recanalization at each step. CA, contact aspiration; EVT, endovascular thrombectomy; LVO, large vessel occlusion; SR, stent retriever.

    View this table:
    Table 1

    Comparison between stent retriever first (SR-first) and contact aspiration first (CA-first) groups

    View this table:
    Table 2

    Comparison between patients with and without rescue treatment

    View this table:
    Table 3

    Predictors of the need for rescue treatment

    View this table:
    Table 4

    Predictors for a good outcome in patients with recanalization success

    Discussion

    The major findings of this study were (1) there was no difference between SR and CA first-line modality in the final recanalization rate, (2) recanalization with the first-line modality alone and first-pass recanalization rates were higher in SR-first, (3) CA-first was independently associated with the need for RT, and (4) RT was negatively associated with a good outcome.

    Interms of performance of EVT devices, most studies have focused on the final recanalization rate.2–4 SR and CA are the two main modalities currently used for EVT and the techniques and devices of each modality have steadily evolved to achieve more recanalization. In this analysis, there was no difference in the final successful recanalization rate between SR and CA first-line modality, which is in line with a previous randomized trial comparing the same two first-line modalities.2 In real practice, a failure of the first-line modality to achieve satisfactory recanalization is not a rare instance. In such LVOs that were refractory to first-line modality, RT was often required. Because successful recanalization is one of the most important factors for a good outcome,12 13 20 it seems a reasonable strategy that RT is performed after the first-line modality failure rather than aborting further treatment. There have been various type of RT, involving switching strategy (changing the first-line modality for the other or the simultaneous use of both modalities), balloon angioplasty, permanent stenting, thrombolytics or glycoprotein IIb/IIIa antagonist administration, or any combination of these.14–18 However, if recanalization can be achieved using the first-line modality and furthermore by first-pass, it would most likely be better than if recanalization was achieved only after RT was applied. Therefore, the analysis of this study was focused on (1) whether there was any difference between CA-first and SR-first on the need for RT and (2) how RT requirement actually affected clinical outcome.

    A significantly higher rate of RT was needed in the CA-first group. Furthermore, CA-first remained independently associated with requiring RT after adjustment for other potential factors, which corresponds well with previous studies. A recent randomized clinical trial showed that successful recanalization rate (83.1% vs 85.4%) and good outcome (50% vs 45.3%) do not differ between SR and CA first-line modalities. However, the need of RT was numerically higher in the CA-first (32.8%) compared with the SR-first (23.8%).2 Also in another observational comparative study, the rate of the use of additional devices was higher in the CA-first (45.2%) than in the SR-first (13.5%).4 In those studies, however, whether there was any difference between SR-first and CA-first in procedural details was not evaluated, nor was whether the clinical outcome was different between recanalization with first-line modality alone and recanalization obtained after RT.

    RT use and more passes of the EVT device may be meaningful independent predictors of poor clinical outcome.18–22 Therefore, if recanalization was achieved in first-pass or, at least, the first-line modality alone without RT, there would be a greater chance of a good outcome. In fact, the recanalization group with RT was independently and negatively associated with a good outcome in this study.

    Various types of RT were used in this study. Switching strategy was significantly higher in CA-first, while rescue stenting and intra-arterial urokinase administration were higher in the SR-first. This seems to indicate that the causes of recanalization failure might differ between SR-first and CA-first. The causes of recanalization failure may be various, including hard (organized) clot, a large volume of clot, and in-situ occlusion of underlying intracranial atherosclerotic stenosis.23–25 It was beyond the scope of this study to investigate the difference in the causes of recanalization failure between SR-first and CA-first. The different causes of recanalization failure and optimizing the strategy of currently available EVT methods should be investigated in further studies.

    Thisstudy has several inherent limitations and strengths. The results should be interpreted with the caution of selection bias. However, the study population was recruited from the prospectively maintained registries of each participating center and clinical variables, including stroke risk factors between the two groups, showed a balanced distribution. Therefore, it did not seem a determinant of the major findings. Because the two modalities are quite different in the mechanisms of action and procedural technique, procedural outcomes seemed to be affected not only by the first-line modality itself but also by the operators’ experience. In addition, because of the retrospective nature of this study, it was not predefined what number of passes determined a failure. However, the operators who participated in this study selected the device they had most experience with as the first-line modality. It is not surprising that RT was negatively associated with good outcome, because similar results were previously reported in the ASTER trial. However, the study population represented at least 15% of all real-world patients who received EVT in our country during the study period, which were inferred from nationwide data of the Health Insurance Review and Assessment Service. Therefore, it is worthy of note that the results of this study would reflect the EVT situation in real-world practice.

    Conclusion

    SR and CA first-line modalities showed no difference in final recanalization rate. However, CA-first was associated with requiring RT, while recanalization with the first-line modality alone and first-pass recanalization rates were significantly higher in the SR-first patients. RT requirement was negatively associated with a good outcome.

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    Footnotes

    • D-HK and JWK contributed equally.

    • Contributors BMK conceptualized the study, performed the analysis, and wrote the manuscript. DHK and JWK assisted in data collection, adjudication of imaging and clinical data, and wrote the manuscript. All authors acquired and analyzed data.

    • Funding This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HC15C1056).

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Additional data from this project can be acauired by contacting the corresponding author.

    • Patient consent for publication Not required.