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Based on results from several studies, recombinant tissue plasminogen activator (rTPA) is approved for use in ischemic stroke only within 3 hours after symptom onset. However, other studies have suggested benefits even after a delay to treatment of more than 3 hours (JW Neurol May 20 2004). In an observational industry-sponsored study, investigators used data from an international registry of thrombolysis (involving more than 700 centers in 35 countries) to compare outcomes in 664 patients who received alteplase (0.9 mg/kg) at 3.0 to 4.5 hours after symptom onset and 11,865 patients who received it within 3 hours after onset.
Functional status at 3 months was similar in the two groups; independence (modified Rankin score ≤2) was achieved by 58% of patients in the group treated at 3.0 to 4.5 hours and by 56% in the group treated within 3 hours (a nonsignificant difference). Rates of symptomatic intracerebral hemorrhage within 24 hours (2.2% vs. 1.6%, respectively) and mortality at 3 months (12.7% vs. 12.2%, respectively) also did not differ significantly between groups.
Wahlgren N et al. Thrombolysis with alteplase 3–4·5 h after acute ischaemic stroke (SITS-ISTR): An observational study. Lancet 2008 Sep 15; [e-pub ahead of print]. (http://dx.doi.org/10.1016/S0140-6736(08)61339-2)
Comment
Although this was not a controlled trial, the study provides evidence that thrombolysis for acute ischemic stroke can be as beneficial at 3.0 to 4.5 hours after symptom onset as within 3 hours. One caveat: The higher rates of mortality and intracerebral hemorrhage in the later-treatment group nearly reached statistical significance (at the P<0.05 level). That finding reinforces what we already know: Overall benefit from thrombolysis is clearly time dependent. Centers that are capable of performing thrombolysis within 3 hours after stroke onset should now consider doing so up to 4.5 hours after onset in patients who are appropriate candidates, particularly young patients with severe deficits. Clearly, nothing is absolute about the 3-hour time window, and thrombolysis should not be withheld for the sole reason that this amount of time has elapsed, particularly if this occurs while preparations for thrombolysis are being finalized. In light of these new findings, acute stroke services and emergency departments should revisit protocols to optimize therapeutic options for patients with this devastating condition.