ABSTRACT NUMBER: ESOC2026A729 THROMBUS LENGTH MODIFIES THE BENEFIT FROM INTRAVENOUS THROMBOLYSIS IN PATIENTS WITH BASILAR ARTERY OCCLUSION: A POST-HOC ANALYSIS OF THE BASICS TRIAL

Abstract Background and aims The benefit from intravenous thrombolysis (IVT) prior to endovascular therapy (EVT) in patients with basilar artery occlusion (BAO) is uncertain. We assessed whether thrombus length modifies the effect of IVT in patients from the BASICS trial. Methods BASICS was a multicenter randomized controlled trial comparing EVT plus best medical management (BMM) versus BMM alone in BAO. We determined thrombus length on baseline CTA and utilized ROC-analysis to stratify cut-off values as additional covariates using regression modelling. We calculated adjusted odds ratios (aOR) for favourable outcome (mRS 0-3 at 90 days), and performed interaction analyses. Results Among 300 BASICS patients, 282 had complete imaging data (median age 69 [IQR 60–76], NIHSS 22 [IQR 11–35], IVT in 226 [80.1%], EVT in 145 [51.4%]). In multivariable analysis, thrombus length >7.5mm (aOR 0.51; 95%CI 0.27–0.99), age (OR 0.97; 95% CI 0.95–1.00), baseline NIHSS (OR 0.91; 95%CI 0.89–0.94), and IVT (OR 2.61; 95%CI 1.07–6.37) were associated with favorable outcome, whereas EVT was not (aOR 1.27; 95%CI 0.67–2.38). Interaction analysis suggested increasing IVT benefit with longer thrombi (interaction OR 1.23; p=0.053). Whereas IVT showed no benefit with thrombi <13mm (aOR 1.27; 95%CI 0.43–3.79), IVT was strongly associated with favourable outcome with thrombi >13mm (aOR 12.24; 95%CI 1.39–108.23; figure). Conclusions IVT and thrombus length are associated with favourable outcome in patients with BAO. While longer thrombi were overall linked to worse prognosis, patients with longer thrombi appear to particularly benefit from IVT. Conflict of interest All authors: nothing to disclose Figure 1 - belongs to Conclusions