By Matthew E. Fink, MD

Louis and Gertrude Feil Professor and Chair, Department of Neurology; Associate Dean for Clinical Affairs, NewYork-Presbyterian/Weill Cornell Medical College

Dr. Fink reports no financial relationships relevant to this field of study.

SOURCE: Johnston SC, Amarenco P, Denison H, et al. Ticagrelor and aspirin or aspirin alone in acute ischemic stroke or TIA. N Engl J Med 2020;383:207-217.

Ticagrelor is a direct-acting antiplatelet agent not dependent on metabolic activation that reversibly binds and inhibits the P2Y receptor on platelets. The Acute Stroke or Transient Ischemic Attack Treated with Ticagrelor and ASA for Prevention of Stroke and Death (THALES) study was designed to test the hypothesis that 30-day treatment with ticagrelor and aspirin would be superior to aspirin alone in reducing the risk of subsequent stroke or death in patients who experienced a non-cardioembolic ischemic stroke or transient ischemic attack (TIA).

This was a randomized, placebo-controlled, double-blind trial that included patients who had experienced mild to moderate ischemic stroke (National Institutes of Health stroke scale score of 5 or lower) or a TIA who were not undergoing thrombolysis or thrombectomy. Within 24 hours, the patients were assigned to receive a 30-day regimen of either ticagrelor plus aspirin or matching placebo plus aspirin. The primary outcome was a composite of recurrent stroke or death within 30 days. Secondary outcomes were the first subsequent ischemic stroke and the incidence of disability within 30 days. The primary safety outcome was severe bleeding.

A total of 11,016 patients were randomized. The primary outcome event occurred in 5.5% of the ticagrelor-aspirin group and in 6.6% in the aspirin-alone group (hazard ratio [HR], 0.83; P = 0.02). Ischemic stroke occurred in 5% of the ticagrelor-aspirin group and 6.3% in the aspirin-alone group (HR, 0.79; P = 0.004). Disability did not differ between the two groups. Severe bleeding occurred in 28 patients in the ticagrelor-aspirin group and in seven patients in the aspirin group.

Johnston et al concluded the combination of ticagrelor and aspirin compared to aspirin alone was superior in reducing the risk of stroke or death within 30 days of an acute ischemic stroke or TIA. However, disability did not differ between the groups. Severe bleeding was more common in the ticagrelor group.