Spe- cifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest. This guideline was approved by the American Heart Association Stroke Council Scientific Statement Oversight Committee on January 19, 2021, and the American Heart Association Executive Committee on April 12, 2021. A copy of the document is available at https://professional.heart.org/statements by using either Search for Guidelines & Statements or the Browse by Topic area. To purchase additional reprints, call 215-356-2721 or email Meredith.Edelman@ wolterskluwer.com. Supplemental materials are available with this article at https://www.ahajournals. org/doi/suppl/10.1161/STR.0000000000000375. The American Heart Association requests that this document be cited as follows: Kleindorfer DO, Towfighi A, Chaturvedi S, Cockroft KM, Gutierrez J, Lombardi-Hill D, Kamel H, Kernan WN, Kittner SJ, Leira EC, Lennon O, Meschia JF, Nguyen TN, Pollak PM, Santangeli P, Sharrief AZ, Smith SC Jr, Turan TN, Williams LS. 2021 Guideline for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline from the American Heart Associa- tion/American Stroke Association. Stroke. 2021;52:e364 e467. doi: 10.1161/ The expert peer review of AHA-commissioned documents (eg, scientific statements, clinical practice guidelines, systematic reviews) is conducted by the AHA Office of Science Operations. For more on AHA statements and guidelines development, visit https://professional.heart.org/statements. Se- lect the Guidelines & Statements drop-down menu, then click Publication Development. Permissions: Multiple copies, modification, alteration, enhancement, and/or distribution of this document are not permitted without the express permission of the American Heart Association. Instructions for obtaining permission are located at https://www.heart.org/permissions. A link to the Copyright Permissions Re- quest Form appears in the second paragraph (https://www.heart.org/en/about- us/statements-and-policies/copyright-request-form). *Former Stroke Scientific Statement Oversight Committee Member, current member during the writing effort. AANS/CNS Liaison. AAN Liaison. 