SOURCE: Johnston SC, Amarenco P, Albers GW, et al. Ticagrelor versus aspirin in acute stroke or transient ischemic attack. N Engl J Med 2016;375:35-43.
The first 90 days after a transient ischemic attack (TIA) or ischemic stroke is a high-risk period for recurrence of cardiovascular thrombotic events. Even with aspirin treatment, recurrences occur in as many as 10-15% of patients. Ticagrelor is an inhibitor of the P2Y12 receptor on platelets, similar in mechanism to clopidogrel. Ticagrelor is indicated for reduction of thrombotic events in persons with acute coronary syndromes or ST-elevation myocardial infarction. Might a different mechanism of action than aspirin treatment, as provided by ticagrelor, reduce thrombotic events in patients who experience a TIA?
The SOCRATES trial enrolled patients (n = 13,199) who had suffered an ischemic stroke or TIA within 24 hours of the event. Study subjects were randomized to ticagrelor (180 mg loading dose, then 90 mg twice per day) or aspirin (300 mg loading, then 100 mg once per day) for 90 days. The primary outcome was a composite of stroke, myocardial infarction, or death.
Although results trended favorably in the ticagrelor treatment arm (hazard ratio = 0.89), they were not statistically significant. Since the treatment costs of aspirin are substantially less than ticagrelor, and the adverse bleeding effect profile is similar, aspirin should remain the drug of choice, except for patients who are aspirin-intolerant.