First-Pass Recanalization with EmboTrap II in Acute Ischemic Stroke (FREE-AIS): A Multicenter Prospective Study

Jang Hyun Baek, Byung Moon Kim, Sang Hyun Suh, Hong Jun Jeon, Eun Hyun Ihm, Hyungjong Park, Chang Hyun Kim, Sang Hoon Cha, Chi Hoon Choi, Kyung Sik Yi, Jun Hwee Kim, Sangil Suh, Byungjun Kim, Yoonkyung Chang, So Yeon Kim, Jae Sang Oh, Ji Hoe Heo, Dong Joon Kim, Hyo Suk Nam, Young Dae Kim

Research output: Contribution to journalArticlepeer-review


Objective: We aimed to evaluate the efficacy of EmboTrap II in terms of first-pass recanalization and to determine whether it could yield favorable outcomes. Materials and Methods: In this multicenter, prospective study, we consecutively enrolled patients who underwent mechanical thrombectomy using EmboTrap II as a front-line device. The primary outcome was the first pass effect (FPE) rate defined by modified Thrombolysis In Cerebral Infarction (mTICI) grade 2c or 3 by the first pass of EmboTrap II. In addition, modified FPE (mFPE; mTICI grade 2b-3 by the first pass of EmboTrap II), successful recanalization (final mTICI grade 2b-3), and clinical outcomes were assessed. We also analyzed the effect of FPE on a modified Rankin Scale (mRS) score of 0-2 at 3 months. Results: Two hundred-ten patients (mean age ± standard deviation, 73.3 ± 11.4 years; male, 55.7%) were included. Ninety-nine patients (47.1%) had FPE, and mFPE was achieved in 150 (71.4%) patients. Successful recanalization was achieved in 191 (91.0%) patients. Among them, 164 (85.9%) patients underwent successful recanalization by exclusively using EmboTrap II. The time from groin puncture to FPE was 25.0 minutes (interquartile range, 17.0-35.0 minutes). Procedure-related complications were observed in seven (3.3%) patients. Symptomatic intracranial hemorrhage developed in 14 (6.7%) patients. One hundred twenty-three (58.9% of 209 completely followed) patients had an mRS score of 0-2. Sixteen (7.7% of 209) patients died during the follow-up period. Patients who had successful recanalization with FPE were four times more likely to have an mRS score of 0-2 than those who had successful recanalization without FPE (adjusted odds ratio, 4.13; 95% confidence interval, 1.59-10.8; p = 0.004). Conclusion: Mechanical thrombectomy using the front-line EmboTrap II is effective and safe. In particular, FPE rates were high. Achieving FPE was important for an mRS score of 0-2, even in patients with successful recanalization.

Original languageEnglish
Pages (from-to)145-154
Number of pages10
JournalKorean Journal of Radiology
Issue number2
StatePublished - Feb 2023

Bibliographical note

Publisher Copyright:
© 2023 The Korean Society of Radiology.


  • First-pass recanalization
  • Stent
  • Stroke
  • Thrombectomy


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