Effect of Thrombectomy With Combined Contact Aspiration and Stent Retriever vs Stent Retriever Alone on Revascularization in Patients With Acute Ischemic Stroke and Large Vessel Occlusion: The ASTER2 Randomized Clinical Trial

Abstract

Importance: Mechanical thrombectomy using a stent retriever or contact aspiration is widely used for treatment of patients with acute ischemic stroke due to anterior circulation large vessel occlusion, but the additional benefit of combining contact aspiration with stent retriever is uncertain.

Objective: To determine whether mechanical thrombectomy for treatment of anterior circulation large vessel occlusion stroke with initial contact aspiration and stent retriever combined results in better final angiographic outcome than with standard stent retriever alone.

Design, setting, and participants: This trial was a multicenter randomized, open-label, blinded end point evaluation that enrolled 408 patients from October 16, 2017, to May 29, 2018, in 11 French comprehensive stroke centers, with a 12-month outcome follow-up. Patients with a large vessel occlusion in the anterior circulation were included up to 8 hours after symptom onset. The final date of follow-up was June, 19, 2019.

Interventions: Patients were randomly assigned (1:1 allocation) to receive initial thrombectomy with contact aspiration and stent retriever combined (205) or stent retriever alone (203).

Main outcomes and measures: The primary outcome was the rate of expanded Thrombolysis In Cerebral Infarction score of 2c or 3 (eTICI 2c/3; ie, scores indicate near-total and total reperfusion grades) at the end of the procedure.

Results: Among the 408 patients who were randomized, 3 were excluded, and 405 (99.3%) patients (mean age, 73 years; 220 [54%] women and 185 [46%] men) were included in the primary analysis. The rate of eTICI 2c/3 at the end of the endovascular procedure was not significantly different between the 2 thrombectomy groups (64.5% [131 of 203 patients] for contact aspiration and stent retriever combined vs 57.9% [117 of 202 patients] for stent retriever alone; risk difference, 6.6% [95% CI, -3.0% to 16.2%]; adjusted odds ratio [OR], 1.33 [95% CI, 0.88 to 1.99]; P = .17). Of 14 prespecified secondary efficacy end points, 12 showed no significant difference. A higher rate of successful reperfusion was achieved in the contact aspiration combined with stent retriever group vs the stent retriever alone group (eTICI 2b50/2c/3, 86.2% vs 72.3%; adjusted OR, 2.54 [95% CI, 1.51 to 4.28]; P < .001) and of near-total or total reperfusion (eTICI 2c/3, 59.6% vs 49.5%; adjusted OR, 1.52 [95% CI, 1.02 to 2.27]; P = .04) after the assigned initial intervention alone.

Conclusions and relevance: Among patients with acute ischemic stroke due to large vessel occlusion, an initial thrombectomy technique consisting of contact aspiration and stent retriever combined, compared with stent retriever alone, did not significantly improve the rate of near-total or total reperfusion (eTICI 2c/3) at the end of the endovascular procedure, although the trial may have been underpowered to detect smaller differences between groups.

Trial registration: ClinicalTrials.gov Identifier: NCT03290885.

Figure 1.. Flowchart of Participation in the ASTER2 Trial

^aRandomization by minimization was implemented to ensure a balance between treatment groups on the variables of center and patients’ age (≤70 vs >70 years), prior use of intravenous thrombolysis, and occlusion site (isolated middle cerebral artery vs others). ^bReasons: 1 patient was transferred to another hospital before thrombectomy, 1 was not treated using a balloon-guide catheter (device unavailable), 1 was not treated due to hemorrhagic transformation before groin puncture, and 1 was treated with aspiration by guiding catheter. ^cDeferred consent could not be obtained for 1 patient because the patient was not competent and no legally authorized representative was available to provide proxy consent. ^dIncludes 1 death that occurred after 12-month follow-up (at 451 days).

Figure 2.. Distribution of the Modified Rankin Scale Score at Baseline (prestroke), 3 Months, and 12 Months

The modified Rankin Scale score measures the degree of disability (score range, 0 [symptom free] to 6 [dead]). The common adjusted odds ratio for a 1-point improvement in the modified Rankin Scale score associated with the combined contact aspiration and stent retriever group was 0.93 (95% CI, 0.64 to 1.34; P = .68) at 3 months and 0.91 (95% CI, 0.61 to 1.35; P = .65) at 12 months. CA indicates contact aspiration; SR, stent retriever.