Susceptibility Vessel Sign and Intravenous Alteplase in Stroke Patients Treated with Thrombectomy: A Secondary Analysis of the SWIFT DIRECT Trial

Background: The susceptibility vessel sign (SVS) on baseline MRI in acute ischemic stroke patients has been associated with better outcomes post-thrombectomy. This study aimed to investigate whether the presence of the SVS modifies the treatment effect of intravenous thrombolysis plus endovascular thrombectomy (IVT + EVT) versus thrombectomy alone (EVT alone). Methods: In this secondary analysis of the SWIFT DIRECT trial, comparing IVT + EVT versus EVT alone, treatment effect and its heterogeneity were assessed with rates of pre-interventional reperfusion (eTICI 2a–3) and successful post-interventional reperfusion (eTICI of 2b–3) according to the SVS status using adjusted multivariable logistic regression. Secondary objectives were to analyze whether the presence of SVS or its individual characteristics (location, length, width, overestimation ratio, two-layered sign) were associated with outcomes. Results: 197 of the initial 408 trial participants were included in this secondary analysis, of which 52% received IVT + EVT. SVS was present in 92% of the participants (n = 181). There was no evidence for treatment effect heterogeneity regarding the post-interventional radiological and clinical effects of IVT + EVT versus EVT alone with strata of SVS. In SVS+ participants, IVT favored pre-interventional reperfusion (aOR 7.95, 95% CI 1.42–44.46), whereas in SVS-patients, it did not (P for interaction = 0.02). The individual SVS characteristics showed no significant associations with outcomes. Conclusion: Presence of SVS does not seem to modify the effect of IVT + EVT versus EVT alone. In SVS+ patients, IVT might improve pre-interventional reperfusion. There is insufficient evidence to recommend using SVS to inform IVT decisions prior to EVT.