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• Response to “Impact of balloon guiding catheter on technical and clinical outcomes: a systematic review and meta-analysis”
  Jin Pyeong Jeon, Jun Hyong Ahn and Sung-Eun Kim
  Published on: 10 May 2018
• Comments on Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis
  Michel Piotin, Raphaël Blanc and Bertrand Lapergue
  Published on: 4 April 2018

• Published on: 10 May 2018

  Response to “Impact of balloon guiding catheter on technical and clinical outcomes: a systematic review and meta-analysis”

  • Jin Pyeong Jeon, Neurosurgeon Hallym University College of Medicine
  • Other Contributors:
    • Jun Hyong Ahn, neurosurgeon
    • Sung-Eun Kim, Emergency medicine doctor

  I read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
  First, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
  In this letter, we made a funnel plot for successful recanalization based on the revised number of events we h...

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  I read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
  First, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
  In this letter, we made a funnel plot for successful recanalization based on the revised number of events we had corrected. However, the funnel plot showed an asymmetry indicative of possible publication bias. To resolve publication bias in deciding on successful recanalization, we trimmed one study. After correction of the forest plot, the adjusted OR was 1.430 (95% CI: 0.852-2.400), suggesting that there was no significant relationship between BGC use and a higher successful recanalization rate (Fig. 2). We think that heterogeneity across studies, in particular thrombus location, can explain the controversial results. Although we did not have accurate information about thrombus location in the studies, which were conference abstract,3-5 difference in posterior circulation may bias the result. For example, we made an additional forest plot based on published articles including two studies6,7 that were not enrolled in the previous meta-analysis1 (Fig. 3A). Our study also demonstrated a higher successful recanalization rate in the BGC group than in the non-BGC group (OR, 2.324; 95% CI: 1.228-4.396). However, possible publication bias was noted, and adjusted OR, after trimming two studies, was 1.630 (95% CI: 0.870-3.053) (Fig.3B). Consequently, we did subgroup analysis for studies that included only anterior circulation stroke patients. Subgroup analysis revealed that the BGC group exhibited a significantly higher successful recanalization rate without heterogeneity (OR, 3.187; 95% CI: 1.797-5.652, Fig. 4A). In addition, publication bias was not observed via the funnel plot (Fig. 4B) or Egger’s regression (p=0.979). Therefore, we think that clot location should be considered to interpret the results.
  Per your comments, when using a BGC, some neurointerventionists including us (JHA and JPJ) can be reluctant to use BGC for patients with difficult arches or have concerns about larger 8Fr or 9Fr groin sheath due to complications. As your conclusion, we hope that further randomized trials can give an answer about the BGC feasibility during mechanical thrombectomy for acute stroke patients.

  References
  1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: A systematic review and meta-analysis. J Neurointerv Surg. 2018;10:335-9.
  2. Nguyen TN, Malisch T, Castonguay AC, et al. Balloon guide catheter improves revascularization and clinical outcomes with the solitaire device: Analysis of the north american solitaire acute stroke registry. Stroke. 2014;45:141-5.
  3. Nguyen TN, Castonguay AC, Nogueira RN, et al. Balloon guide catheter improved clinical outcomes, revascularization, and decreased mortality in Trevo thrombectomy. Analysis of the TREVO Stent Retreiver acute stroke (TRACK) Registry. Presentated at the Society of Vascular Interventional Neurology Conference. 2015
  4. Zaidat O, Froehler MT, Aziz-Sulta MA, et al. Influce of balloon, conventional or distal catheters on angigraphic and clinical otucomes in the Stratis Registry. Stroke. 2017
  5. Zaidat O, Liebeskind D, Jahan R, et al. Influce of balloon, conventional, or distal catheters on angigraphic and technical otucomes in STRATIS. J Neurointerv Surg. 2016.
  6. Lee DH, Sung JH, Kim SU, et al. Effective use of balloon guide catheters in reducing incidence of mechanical thrombectomy related distal embolization. Acta Neurochir (Wien). 2017;159:1671-7.
  7. Oh JS, Yoon SM, Shim JJ, et al. Efficacy of balloon-guiding catheter for mechanical thrombectomy in patients with anterior circulation ischemic stroke. J Korean Neurosurg Soc. 2017;60:155-64.

  Figure legends
  Figure 1. Revised forest plot of successful recanalization events according to the use of a balloon guiding catheter (BGC) during mechanical thrombectomy.
  Figure 2. Funnel plots of the unadjusted and adjusted effect estimates after correction of publication bias using the “trim and fill” method for successful recanalization. The white circles indicate individual original studies, and the white diamond is the odds ratio (OR) and 95% confidence interval for the meta-analysis. The data point for imputed studies are highlighted in black, and the pooled effect by the recomputation is the black diamond.
  Figure 3. A, Comparisons of mechanical thrombectomy for successful recanalization between the BGC group vs. the non-BGC group, based on published full-text articles. B, Funnel plots of the unadjusted and adjusted effect estimates after correction of publication bias using the “trim and fill” method.
  Figure 4. A, Subgroup analysis of successful recanalization between the BGC group vs. the non-BGC group, based on published full-text articles that included only anterior circulation stroke. B, Funnel plots of the publication bias.

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  Conflict of Interest:
  None declared.

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• Published on: 4 April 2018

  Comments on Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis

  • Michel Piotin, interventional neuroradiologist Foundation Rothschild Hospital
  • Other Contributors:
    • Raphaël Blanc, interventional neuroradiologist
    • Bertrand Lapergue, neurologist

  We read with interest the meta-analysis conducted by our colleague Dr Waleed Brinjikji (1). In the text (section "Limitations", he stated: "Data from the Interest of Direct Aspiration First Pass Technique (ADAPT) for Thrombectomy Revascularization of Large Vessel Occlusion in Acute Ischemic Stroke (ASTER) trial suggest that there were no statistically significant differences in revascularization rates when performing the ADAPT technique compared with using a stent retriever. However, it is unclear at this time whether BGCs were used in this trial."
  Nevertheless in our publication of the ASTER trial results (2), we clearly stated in the Results section that a balloon-guide catheter was used to allow proximal flow arrest during stent retriever removal in 92% of patients treated with the stent retriever technique.
  1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis. J Neurointerv Surg 2018;10:335–339.
  2. Lapergue B, Blanc R, Gory B, et al. JAMA. 2017;318:443-452.

  Conflict of Interest:
  None declared.

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