LMWH IV alteplase should not be administered to patients who have received a full treatment dose of LMWH within the previous 24 h. (COR III: Harm; LOE B-NR) (Recommendation wording modified to match COR III stratifications.) (Continued) Thrombin inhibitors or factor Xa inhibitors The use of IV alteplase in patients taking direct thrombin inhibitors or direct factor Xa inhibitors has not been firmly established but may be harmful. (COR III: Harm; LOE C-EO) IV alteplase should not be administered to patients taking direct thrombin inhibitors or direct factor Xa inhibitors unless laboratory tests such as aPTT, INR, platelet count, ecarin clotting time, thrombin time, or appropriate direct factor Xa activity assays are normal or the patient has not received a dose of these agents for >48 h (assuming normal renal metabolizing function). (Alteplase could be considered when appropriate laboratory tests such as aPTT, INR, ecarin clotting time, thrombin time, or direct factor Xa activity assays are normal or when the patient has not taken a dose of these ACs for >48 h and renal function is normal.) (Recommendation wording modified to match COR III stratifications.) Concomitant Abciximab Abciximab should not be administered concurrently with IV alteplase. (COR III: Harm; LOE B-R) Concomitant IV aspirin IV aspirin should not be administered within 90 min after the start of IV alteplase. (COR III: Harm; LOE B-R) Infective endocarditis For patients with AIS and symptoms consistent with infective endocarditis, treatment with IV alteplase should not be administered because of the increased risk of intracranial hemorrhage. (COR III: Harm; LOE C-LD) (Recommendation wording modified to match COR III stratifications.) Aortic arch dissection IV alteplase in AIS known or suspected to be associated with aortic arch dissection is potentially harmful and should not be administered. 