By Matthew E. Fink, MD
Professor and Chairman, Department of Neurology, Weill Cornell Medical College; Neurologist-in-Chief, New York Presbyterian Hospital
SOURCE: Johnstone SC, Amarenco P, Albers GW, et al for the SOCRATES Steering Committee and Investigators. Ticagrelor versus aspirin in acute stroke or transient ischemic attack. N Engl J Med 2016;375:35-43.
The 90 days following ischemic stroke or transient ischemic attack pose serious risk of subsequent ischemic event. Traditionally the standard supplementary preventative treatment is a daily dose of aspirin. On a long-term basis, however, the efficacy of this treatment yields only a 20% reduction in rate of recurrent stroke when compared with no preventative therapy at all. As such, alternative therapies with higher levels of efficacy have been highly sought-after. One potential alternative is ticagrelor, a direct-acting antiplatelet agent that inhibits the P2Y12 receptor on platelets. Ticagrelor theoretically would prove more effective than either aspirin or clopidogrel. The trial, then, was conducted to test the comparative effectiveness of secondary prevention between two secondary preventative treatments, ticagrelor and aspirin.
The international, double-blind, controlled trial spanned 33 countries and 674 medical centers, enlisting 13,199 patients with either ischemic stroke or transient ischemic attack. Patients with severe ischemic stroke were excluded from consideration. Subjects without cardioembolic stroke were randomly assigned, in a 1:1 ratio, to a daily regimen of either ticagrelor or aspirin for the following 89 days. The primary endpoints measured were the time to occurrence of stroke, myocardial infarction or death within the 90-day treatment. During treatment, 6.2% of patients in the ticagrelor group experienced a primary endpoint, compared with 7.5% of patients in the aspirin group. There was also not a significant difference between rates of major bleeding episodes or incidence of intracranial hemorrhage.
Contrary to prior assumptions about the efficacy of ticagrelor, the antiplatelet treatment was not found to the superior to aspirin in the reduction of stroke risk, risk for myocardial infarction, or risk of death within 90 days. There was, however, a trend that demonstrated a reduction in the rate of ischemic stroke. That trend was not statistically significant.