Personalized Antiplatelet Secondary Stroke PRevenTion

Inclusion Criteria: * Provide signed and dated informed consent form. * Willing to comply with all study procedures and be available for the duration of the study. * Meet criteria for a mild or moderate ischemic stroke or high-risk TIA * Ability to randomize within 30 hours of stroke symptom onset/last seen normal time Exclusion Criteria: * Evidence of new or prior non-traumatic intracerebral hemorrhage, subarachnoid hemorrhage, or subdural hemorrhage on initial head CT * Evidence of a central nervous system tumor, abscess, intracranial aneurysm or vascular/structural malformation, or any neuro-inflammatory, neuro-infectious, or neurodegenerative disorder on neuroimaging or exam that could confound a participant's functional outcome * Isolated or pure sensory symptoms (e.g., numbness), visual changes, or "dizziness"/vertigo without evidence of acute ischemic stroke on baseline head CT or MRI. * Qualifying ischemic event is believed to be iatrogenic or procedure related * Required to take a specific antiplatelet medication for an indication other than ischemic stroke during the study period that would prevent the investigator from following the study algorithm * Etiology of qualifying ischemic event is known to be cardioembolic * High likelihood that anticoagulation will be needed during the study period. * High likelihood that carotid endarterectomy or carotid stenting will occur during the period of the study. * Pre-stroke modified Rankin scale (mRS) score ≥ 3 * Evidence of frailty * Contraindication to aspirin, clopidogrel, Aggrenox®, or ticagrelor * Known allergy or hypersensitivity that would prevent the investigator from following the study algorithm * Any history of moderate to severe drug-induced adverse events * Renal insufficiency or history of kidney transplant * Hepatic impairment, international normalized ratio (INR) \> 1.5, physical manifestations of liver disease, or history of liver transplant * Class II, III, or IV New York Heart Association (NYHA) functional heart failure * Any history of bradycardia without pacemaker placement * Active obstructive lung disease * Any active hematologic disorder * Active bleeding diathesis * Any systemic hemorrhage or GI bleed in the 3 months prior to the qualifying stroke * Active peptic ulcer disease * Women who self-report that they are pregnant or breastfeeding * Active alcohol or substance abuse or dependence * Inability or failure to provide informed consent. * Inability of the patient to adhere to study procedures and/or follow-up, in the opinion of the investigative team * Inability to swallow oral medications * Not willing or able to discontinue prohibited concomitant medications * Ongoing participation in another non-observational clinical study * Life expectancy \< 1 year, in the opinion of the investigative team