Variation in Vessel Size and Angiographic Outcomes Following Stent-Retriever Thrombectomy in Acute Ischemic Stroke: STRATIS Registry

Background: Mechanical thrombectomy is established for large-vessel occlusions in acute ischemic stroke, but the potential role in distal vessel occlusions of medium arteries is less well established. Such medium or distal arterial segments have not been assessed with respect to thrombectomy devices used during endovascular therapy. We conducted an analysis of arterial size, segmental anatomy, and stent-retriever device performance with respect to vessel size during thrombectomy. Methods: The STRATIS registry angiography core laboratory adjudicated the exact location of the occlusion, proximal, and distal device deployment, relationship to arterial bifurcations, and anatomic nomenclature. Arterial diameters were measured at all these sites. Statistical analyses examined the relationship between vessel and stent size, and arterial recanalization using expanded Thrombolysis in Cerebral Infarction reperfusion score. Results: Overall, 665 patients with stroke were included following thrombectomy using various Solitaire device sizes, including Solitaire 4x40, Solitaire 6x30, Solitaire 4x20, Solitaire 6x20, and Solitaire 4x15. Arterial diameter at the occlusion site was a median of 2.17 mm (interquartile range [IQR], 1.88-2.60 mm) in the distal M1, 1.67 mm (IQR, 1.47-2.06 mm) in the proximal M2 middle cerebral artery, 1.50 mm (IQR, 1.15-1.61 mm) in the distal M2 middle cerebral artery, 1.24 mm (IQR, 1.11-1.24 mm) in the M3 middle cerebral artery, and 1.88 mm (IQR, 1.49-1.94 mm) in the P1 posterior cerebral artery. Expanded Thrombolysis in Cerebral Infarction 2b to 3 reperfusion was achieved in all M3 or P1 segment occlusions. The rate of first-pass recanalization was significantly higher in patients with medium (0.75-2 mm) versus large (>2 mm) vessel occlusion (69.5% versus 57.1%; P = 0.003). Conclusion: Considerable overlap was noted between arterial sizes at occlusion sites carrying different segmental arterial nomenclature or vessel names. Substantial reperfusion may be achieved with currently available mechanical thrombectomy devices in medium arteries.