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Impact of Stent Retriever Size on Clinical and Angiographic Outcomes
Study Questions:
How does stent retriever size impact clinical and angiographic outcomes in acute ischemic stroke patients with large vessel occlusion (LVO) who undergo mechanical thrombectomy?
Methods:
This is a retrospective analysis of data from the STRATIS 55-site registry, which included 715 acute ischemic stroke patients with LVO treated with thrombectomy with a Solitaire stent retriever. Retrievers of 4x20, 4x40, and 6x30 (diameter x length) millimeters were compared. Included patients had anterior circulation LVO, were treated within 8 hours of stroke symptom onset, and had a National Institutes of Health Stroke Scale score of 8-30. The primary radiographic outcome was first-pass effect (FPE), defined as achievement of near-complete (mTICI 2c) or complete (mTICI 3) flow following a single device pass without the use of rescue therapy. Adjunctive techniques (such as balloon guidance) were permitted. The primary clinical outcome was prevalence of functional independence (modified Rankin scale score 0-2) at 90 days post-stroke.
Results:
The 4x20 stent retriever was used in 201 (28%) patients, 4x40 was used in 270 (38%) patients, and the 6×30 was used in 244 (34%) patients. No significant difference in FPE was seen between the 4x40 and 4x20 groups, nor between the 4x20 and the 6x30 groups. However, 49% of the 4x40 group achieved FPE compared to 36% of the 6x30 group (p = 0.003). There were no significant differences in functional independence at 90 days across the three stent groups. Although it was not a primary outcome, the final (not just first-pass) mTICI score achieved did not differ across the three groups.
Conclusions:
In this retrospective analysis of acute ischemic stroke patients with LVO, the 4x40 Solitaire stent retriever was associated with higher rates of FPE than the 6x30 stent retriever. No difference in FPE was observed between the 4x40 and 4x20 stents, nor between the 4x20 and 6x30 stents. No difference in clinical outcomes was observed across the three stent groups.
Perspective:
The results of this study are unlikely to change practice given their observational nature and susceptibility to confounding factors. Selection of stent size is likely dependent on center, operator, and unmeasurable patient factors, and these factors themselves may affect angiographic and clinical outcomes. A randomized controlled trial would be required to more confidently define which stent retriever size is safest and most effective. However, such a study would involve considerable expense and may be hampered by strong operator preferences regarding device selection.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Cardiac Surgery and Arrhythmias, Interventions and Imaging, Interventions and Vascular Medicine, Angiography, Nuclear Imaging
Keywords: Angiography, Brain Ischemia, Cerebrovascular Disorders, Outcome Assessment, Health Care, Secondary Prevention, Stents, Stroke, Thrombectomy, Vascular Diseases
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