Quantitative analysis of thrombus migration before mechanical thrombectomy: Determinants and relationship with procedural and clinical outcomes

Abstract

Background and purposeIn patients with acute ischemic stroke (AIS) and a large vessel occlusion (LVO), thrombus migration (T-Mig) is a common phenomenon before mechanical thrombectomy (MT), revealed by pre-treatment imaging. Previous works have used qualitative scales to define T-Mig. The aim of this study was to evaluate the determinants and impact of quantitatively assessed T-Mig on procedural characteristics and clinical outcome. MethodsConsecutive patients with AIS due to LVO treated by MT at a reference academic hospital were analysed. Distance between vessel origin and beginning of the thrombus on MRI (3D-time-of-flight and/or contrast-enhanced magnetic-resonance-angiography) and digital-substracted-angiography (DSA) were measured in millimeters using a curve tool. Thrombus migration was defined quantitatively as ∆TD calculated as the difference between pre-MT-DSA and MRI thrombus location. ∆TD was rated as significant if above 5mm. ResultsA total of 267 patients were included (mean age 70±12 years; 46% females) were analyzed. Amongst them, 65 (24.3%) experienced any degree of T-Mig. T-Mig was found to be associated with iv-tPA administration prior to thrombectomy (β-estimate 2.52; 95% CI [1.25–3.79]; p<0.001), fewer device passes during thrombectomy (1.22±1.31 vs 1.66±0.99; p<0.05), and shorter pre-treatment thrombi (β-estimate -0.1millimeter; 95% CI [-0.27–0.07]; p<0.05). There was no association between T-Mig and a favourable outcome (defined by a 0-to-2 modified-Rankin-Scale at 3months, adjusted OR: 2.16 [0.93 – 5.02]; p=0.06) ConclusionThrombus migration happens in almost a fourth of our study sample, and its quantitative extent was associated with iv-tPA administration prior to MT, but not with clinical outcome.