<prompt> IV thrombolysis is of no use in ischaemic stroke beyond6 hours12 hours18 hours24 hours  <response>: In IV PA trails, efficacy was confirmed in the 3-h time window, and efficacy likely extended to 4.5 h and possibly to 6 h.Depending on the country, IV PA is approved for up to 4.5 hCriteria for administration of Intravenous Recombinant Tissue Plasminogen Activator PA for Acute Ischemic Stroke AISClinical diagnosis of strokeOnset of symptoms to time of drug administration 4.5 hCT scan showing no haemorrhage or edema of 13 of the MCA territoryAge 18 yearsConsent by patient or surrogateRef: Harrison 19e pg: 2562 