Inclusion Criteria:

• Age ≥18 years at the time of the index ischemic stroke.
• Confirmed diagnosis of ischemic stroke according to the World Health Organization (WHO) definition.
• Availability of at least one neuroimaging exam (either a non-contrast computed tomography [NCCT] or magnetic resonance imaging [MRI] of the brain) demonstrating one or more ischemic lesions consistent with patient symptoms.
• Ongoing oral anticoagulation at the time of the index ischemic stroke, defined as the last intake within 48 hours prior to stroke symptom onset for patients on direct oral anticoagulants (DOACs), or an international normalized ratio (INR) of ≥1.5 in patients on vitamin K antagonists (VKAs), regardless of the time elapsed between the last intake and stroke symptom onset.
• Prior diagnosis of AF or other cardioembolic arrhythmias.

Exclusion Criteria:

• Symptoms not indicative of acute stroke (i.e., syncope, tonic or clonic activity, dizziness alone, confusion and amnesia alone, chronic or subacute development of focal neurological deficit).
• Ongoing parenteral (intravenous or subcutaneous) anticoagulation at the time of the index event, including bridging with heparin in patients initiating VKA.