Q: According to a 2009 science advisory from the American Heart Association/American Stroke Association - Upto what hours the expansion of the time window can be spread for treatment of acute ischemic stroke with intravenous Tissue Plasminogen Activator?

Answer: 4.5 hours

According to new recommendation:

"rtPA should be administered to eligible patients who can be treated in the time period of 3 to 4.5 hours after stroke (Class I Recommendation, Level of Evidence B). The eligibility criteria for treatment in this time period are similar to those for persons treated at earlier time periods, with any one of the following additional exclusion criteria: Patients older than 80 years, those taking oral anticoagulants with an international normalized ratio less than/=1.7, those with a baseline National Institutes of Health Stroke Scale score more than 25, or those with both a history of stroke and diabetes. Therefore, for the 3-to-4.5–hour window, all patients receiving an oral anticoagulant are excluded regardless of their international normalized ratio. The relative utility of rtPA in this time window compared with other methods of thrombus dissolution or removal has not been established. The efficacy of intravenous treatment with rtPA within 3 to 4.5 hours after stroke in patients with these exclusion criteria is not well established (Class IIb Recommendation, Level of Evidence C) and requires further study".

Expansion of the Time Window for Treatment of Acute Ischemic Stroke With Intravenous Tissue Plasminogen Activator - A Science Advisory From the American Heart Association/American Stroke Association - Stroke. 2009;40:2945.