See Table XCV in online Data Supplement 1 for original wording. 3.9. Antiplatelet Treatment 3.9. Antiplatelet Treatment COR LOE New, Revised, or Unchanged Administration of aspirin is recommended in patients with AIS within 24 to 48 hours after onset. For those treated with IV alteplase, aspirin administration is generally delayed until 24 hours later but might be considered in the presence of concomitant conditions for which such treatment given in the absence of IV alteplase is known to provide substantial benefit or withholding such treatment is known to cause substantial risk. I A Recommendation revised from 2013 AIS Guidelines. The safety and benefit of aspirin in the treatment of patients with AIS were established by 2 large clinical trials This has recently been confirmed by a large Cochrane review of aspirin trials.209 In patients unsafe or unable to swallow, rectal or nasogastric administration is appropriate. Limited data exist on the use of alternative antiplatelet agents in the treatment of AIS. However, in patients with a contraindication to aspirin, administering alternative antiplatelet agents may be reasonable. A retrospective analysis of consecutive ischemic stroke patients admitted to a single center in Seoul, South Korea, found no increased risk of hemorrhage with early initiation of antiplatelet or anticoagulant therapy (<24 hours) after IV alteplase or EVT compared with initiation >24 hours.177 However, this study may have been subject to selection bias, and the timing of initiation of antiplatelet therapy or anticoagulation should be made on an individual level, balancing risk and benefit. The recommendation was modified from the previous guideline to remove the specific dosing recommendation initial dose is 325 mg because previous clinical trials supporting its use for AIS included doses of 160 to 300 mg. See Tables XLII and XLVIII in online Data Supplement 1. 