Posterior circulation stroke accounts for 20-25% of all ischemic strokes, with an annual adjusted incidence of 18 per 100,000 person-years. Compared with anterior circulation stroke, posterior circulation stroke is less studied and has poor neurological outcomes, which requires attention. Intravenous thrombolytic therapy has greatly improved the rate of recanalization and reperfusion in patients with acute ischemic stroke, increased the proportion of patients with good prognosis, and reduced mortality. Guidelines recommend intravenous thrombolysis within 4.5 hours of onset or awakening in patients with ischemic stroke. However, the proportion of posterior circulation stroke is low or unreported in most randomized controlled trials, such as 5% of patients in the NINDS study, so it may be inappropriate to apply the results of these trials directly to patients with posterior circulation ischemic stroke.~Multiple studies have also shown a lower risk of post-circulation bleeding complications compared to pre-circulation stroke. A meta-analysis of patients with posterior circulation ischemic stroke (11.9% of posterior circulation stroke) showed that posterior circulation stroke had a lower risk of intracranial hemorrhage due to intravenous thrombolysis, half the risk of anterior circulation stroke, and a higher 3-month good functional outcome. The lower risk of hemorrhagic transformation in posterior circulation stroke is due to the greater tolerance of the posterior circulation area to ischemic injury, possibly due to a greater proportion of white matter and arterial collaterals, especially in the brainstem. In addition, the smaller infarct size of posterior circulation stroke compared with anterior circulation stroke also reduced the risk of bleeding in these patients.~Therefore, the purpose of this study was to investigate whether patients with posterior circulation stroke with onset or discovery time of 4.5-24 hours could benefit from intravenous thrombolysis in the Chinese population.
The primary hypothesis being tested in this trial is that ischemic stroke patients in posterior circulation at 4.5 - 24 hours post onset of stroke will have improved clinical outcomes when given intravenous tissue plasminogen activator (tPA) compared to standard care.