Thrombolysis in Patients With Versus Without Visible Occlusion: A Secondary Analysis From the AcT Trial

Approximately 70% of patients who present with symptoms of acute ischemic stroke (AIS) have no visible occlusion (NVO) on intracranial computed tomography angiography (CTA). 1 These patients may either have lacunar stroke, intracranial pial arterial occlusions that are not visible on CTA, vascular stenosis resulting in hypoperfusion, spontaneous recanalization, or conditions that are stroke mimics.Owing to these different mechanisms, current data on the safety and efficacy of intravenous thrombolysis in patients with NVO is conflicting. 2,3The aim of the current study, from the phase 3 Alteplase Compared to Tenecteplase in Patients With Acute Ischemic Stroke (AcT) randomized controlled trial, is to report on safety and efficacy outcomes in patients with NVO versus those with visible occlusion (VO) on baseline CTA who received thrombolysis.This sub-study is an exploratory analysis of the AcT trial, which randomized adult patients with stroke symptoms, eligible for intravenous thrombolysis as per guidelines, to either alteplase or tenecteplase. 4,5The trial was regulated by Health Canada and approved by research ethics boards at all participating sites.The trial used deferred consent procedures wherever approved by local research ethics boards.The current analysis included patients with interpretable baseline CT angiogram who received intravenous thrombolysis.An independent blinded imaging core lab with 4-20 years of experience read all imaging data.VO was defined as any occluded artery visualized on baseline CTA.NVO were those patients who did not have any intracranial occlusion on baseline CTA.Safety outcomes included symptomatic intracerebral hemorrhage (sICH) within 24 hours, mortality, and evidence of bleeding on follow-up imaging as per the Heidelberg Bleeding Classification described in the trial protocol 5 (Supplementary Methods).