THALES PRIMARY EFFICACY END POINT
In patients with acute ischemic stroke (NIHSS ≤5) or high-risk TIA, BRILINTA showed a greater reduction in the composite of subsequent stroke or death vs aspirin alone1,2
THALES primary efficacy end point (composite of stroke or death at 30 days)
- The composite end point was driven by the stroke component of the primary end point (19% RRR, 1.1% ARR)2
- BRILINTA is not indicated to reduce death in patients with acute ischemic stroke or high-risk TIA2
- BRILINTA’s treatment effect on stroke and on death accrued over the first 10 days and was sustained at 30 days. Although not studied, this suggests that shorter treatment could result in similar benefit and reduced bleeding risk2
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THALES STUDY DESIGN
THALES was a randomized, international, double-blind, placebo-controlled, multicenter study to investigate dual antiplatelet therapy with BRILINTA (180-mg loading dose, 90 mg twice daily thereafter) and aspirin vs placebo and aspirin in the prevention of stroke or death in patients with acute ischemic stroke or transient ischemic attack (N=11,016). The primary end point was the first occurrence of the composite of stroke or death at 30 days. In both arms, patients received a loading dose of aspirin 300-325 mg followed by aspirin 75-100 mg once daily. Patients were ≥40 years of age, had mild-to-moderate acute noncardioembolic ischemic stroke (NIHSS score ≤5), or high-risk TIA (ABCD2 score ≥6 or symptomatic intracranial or extracranial arterial stenosis [≥50% narrowing in the diameter of the lumen of an artery that could account for the TIA]). Patients were randomized within 24 hours and treated for a median of 31 days.1,2
ABCD2=Age, Blood pressure, Clinical features, Duration of TIA, and Diabetes mellitus; ARR=absolute risk reduction; CI=confidence interval; HR=hazard ratio; K-M=Kaplan-Meier; NIHSS=National Institutes of Health Stroke Scale; NNT=number needed to treat; RRR=relative risk reduction; THALES=Acute STroke or Transient IscHemic Attack Treated with TicAgreLor and Aspirin for PrEvention of Stroke and Death; TIA=transient ischemic attack.
References
- 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(3):207-217 and Supplementary Appendix.
- BRILINTA® (ticagrelor) [package insert]. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2024.
THE THALES STUDY1
11,016 patients were randomized within 24 hours and treated for 30 days1
OBJECTIVE
THALES compared dual antiplatelet therapy (DAPT) with BRILINTA 90 mg and aspirin vs placebo and aspirin in patients with acute ischemic stroke or high-risk TIA for the primary efficacy end point of the composite of stroke or death and the primary safety end point of first GUSTO severe bleeding.
STUDY DESIGN
Randomized, double-blind, placebo-controlled, parallel-group, multicenter trial conducted across 28 countries and 414 sites

Primary efficacy composite end point: Stroke (ischemic and hemorrhagic) or all-cause death
Key secondary efficacy end point: Ischemic stroke
Primary safety end point: GUSTO severe bleeding
Key inclusion criteria
- Patients ≥40 years of age, randomized within 24 hours after onset of symptoms, with:
- Mild-to-moderate acute noncardioembolic ischemic stroke (NIHSS score ≤5 and persistent signs or symptoms at the time of randomization or acute ischemic brain lesion determined by CT scan or MRI)
OR
- High-risk TIA (ABCD2 score ≥6 or with large-vessel disease [ie, ipsilateral ≥50% stenosis of extra- or intracranial artery])
Key exclusion criteria
- Thrombolysis or mechanical thrombectomy within 24 hours before randomization
- Planned use of anticoagulation
- Planned use of antiplatelet therapy other than aspirin
- History of atrial fibrillation/flutter or ventricular aneurysm
- Suspicion of a cardioembolic cause of TIA or stroke
- History of ICH or GI bleeding within the past 6 months or major surgery within 30 days
*Loading doses were given to patients as soon as possible after randomization on day 1.
ABCD2=Age, Blood pressure, Clinical features, Duration of TIA, and Diabetes mellitus; BID=twice daily; CT=computed tomography; GI=gastrointestinal; GUSTO=Global Use of Strategies to Open Occluded Coronary Arteries; ICH=intracranial hemorrhage; LD=loading dose; MRI=magnetic resonance imaging; NIHSS=National Institutes of Health Stroke Scale; QD=once daily; THALES=Acute STroke or Transient IscHemic Attack Treated with TicAgreLor and Aspirin for PrEvention of Stroke and Death; TIA=transient ischemic attack.
Reference: 1. 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(3):207-217, Supplementary Appendix, and Protocol.