Thrombolysis in Patients With Versus Without Visible Occlusion: A Secondary Analysis From the AcT Trial
Bibliographic record
Abstract
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.2,3 The 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.4,5 The 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).Functional outcomes included modified Rankin Scale (mRS) 6 0-1, mRS 0-2, ordinal mRS at 90-120 days, return
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.005 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.003 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".