Category: Neurology
Keywords: ischemic stroke, thrombolysis, tpa, intracranial hemorrhage (PubMed Search)
Posted: 6/6/2025 by Nicholas Contillo, MD
(Updated: 6/21/2025)
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Acute ischemic strokes involving the posterior circulation have significantly lower rates of hemorrhagic transformation after thrombolysis compared to anterior circulation strokes, a difference attributed to smaller infarct sizes and greater “ischemic tolerance” in the posterior circulation.
Given this lower hemorrhage risk, the EXPECTS trial evaluated the safety and efficacy of extending the thrombolysis window to 4.5–24 hours in patients with acute posterior circulation ischemic stroke who were not candidates for endovascular thrombectomy. This randomized controlled trial, conducted across 30 sites in China, enrolled 234 adults with mainly mild posterior circulation stroke (median NIHSS 3) and no evidence of extensive infarction on CT. Participants were randomized to receive either intravenous alteplase or standard medical care within the 4.5–24 hour window after symptom onset.
The primary outcome of functional independence at 90 days (modified Rankin Scale 0–2) was achieved in 89.6% of the alteplase group versus 72.6% of the standard care group. Rates of symptomatic intracranial hemorrhage were low and similar between groups (1.7% alteplase vs. 0.9% standard care), and 90-day mortality was lower in the alteplase group (5.2% vs. 8.5%).
These findings support extending the therapeutic window for intravenous thrombolysis in posterior circulation stroke beyond 4.5 hours when thrombectomy is not an option. However, the trial’s limitations, including a study population predominantly with mild strokes, exclusion of patients with extensive infarction, and enrollment limited to Chinese centers, warrant further investigation in larger and more diverse populations.
Bottom Line: Within limitations, emerging evidence supports an extended thrombolytic window beyond 4.5 hours for patients with posterior circulation strokes who are ineligible for thrombectomy.
Yan S, Zhou Y, Lansberg MG, Liebeskind DS, Yuan C, Yu H, Chen F, Chen H, Zhang B, Mao L, Zhang X, Wang X, Zhang X, Chen Y, Zhou H, Zhong W, He Y, Chen K, Wang J, Chen H, Huang Y, Campbell BCV, Lou M; EXPECTS Group. Alteplase for Posterior Circulation Ischemic Stroke at 4.5 to 24 Hours. N Engl J Med. 2025 Apr 3;392(13):1288-1296. doi: 10.1056/NEJMoa2413344. PMID: 40174223.
