Transient ischemic attack is a common form of stroke, and 1 in 4 stroke survivors go on to experience a second stroke—most within the first month.
Compared with taking aspirin alone, adding the blood thinner ticagrelor for 30 days reduced the combined risk of stroke and death by 17% among patients who previously had suffered an acute ischemic stroke or transient ischemic attack, known as a TIA. These full results from the phase 3 THALES trial were published Thursday in the New England Journal of Medicine.
Aspirin and ticagrelor reduced the rate of ischemic stroke by 21%, compared with taking aspirin alone, up to day 30. Earlier this month, the maker of ticagrelor, AstraZeneca, announced that the FDA had accepted a supplemental New Drug Application and granted priority review for the drug, sold as Brilinta, for the reduction of subsequent stroke in patients who had an acute ischemic stroke or TIA. Under the Prescription Drug User Fee Act, the application will be acted on in the fourth quarter of 2020.
TIA is a common form of stroke, and 1 in 4 stroke survivors go on to experience a second stroke—most within the first month. “Early treatment is important to prevent a subsequent stroke that may be disabling or fatal. It is also expected to improve long-term outcomes,” Clay Johnston, MD, PhD, lead investigator for the THALES trial and dean of the Dell Medical School at The University of Texas in Austin, said in a statement.
Investigators said previous trials had studied the use of clopidogrel and aspirin to prevent stroke after an ischemic stroke TIA, and an earlier trial had found that ticagrelor was not better than aspirin in preventing vascular events or death in these circumstances. But comparing the combination of ticagrelor and aspirin to aspirin alone had not been well studied.
In THALES, 11,016 patients were randomized; 5523 were in the combination group and 5493 were in the aspirin-only group. In the combination group, 303 patients (5.5%) experienced a primary outcome event, while 362 patients (6.6%) did so in the aspirin-only group, for an HR of 0.83 (95% CI, 0.71-0.96; P = .02). Ischemic stroke occurred in 276 patients (5.0%) in the combination group and in 345 patients (6.3%) in the aspirin-only group, for an HR of 0.79 (95% CI, 0.68-0.93; P = .004).
Incidence of disability did not differ significantly between the 2 groups. Severe bleeding occurred in 28 patients (0.5%) in the combination group and in 7 patients (0.1%) in the aspirin-only group (0.001%).
Johnston SC, Amarenco P, Denison H, et al; THALES Investigators. Ticagrelor and aspirin or aspirin alone in acute ischemic stroke or TIA. N Engl J Med. 2020;383:207-217. doi:10.1056/NEJMoa1016870