Discharge Aspirin Dose and Clinical Outcomes in Patients with Acute Coronary Syndromes treated with Prasugrel vs. Clopidogrel: An Analysis from the TRITON-TIMI 38 Study.
J Am Coll Cardiol. 2013 Oct 1;
Authors: Kohli P, Udell JA, Murphy SA, Cannon CP, Antman EM, Braunwald E, Wiviott SD
OBJECTIVES: We sought to investigate whether there is a relationship between aspirin dose and the potent antiplatelet agent prasugrel in the TRITON-TIMI 38 study.
BACKGROUND: Optimal aspirin dosing following acute coronary syndrome remains uncertain. Previous studies have raised questions regarding an interaction between high-dose aspirin and the potent antiplatelet agent ticagrelor.
METHODS: In TRITON-TIMI 38, we classified 12,860 patients into low-dose (<150 mg) or high-dose (≥150 mg) aspirin groups based on discharge dose. We identified independent correlates of dose selection and studied the impact of aspirin dose on clinical effects of prasugrel.
RESULTS: There was significant geographical variation in aspirin dosing, with North American patients receiving high-dose aspirin more frequently than other countries (66% vs. 28%, p<0.001). Clinical factors correlating with high-dose aspirin included prior percutaneous coronary intervention, prior myocardial infarction, and use of aspirin or beta-blockers prior to randomization. Characteristics associated with use of low-dose aspirin included age ≥75 years, white race, and use of bivalirudin or a glycoprotein IIb/IIIa inhibitor during coronary intervention. Regardless of low-dose or high-dose aspirin, prasugrel had lower rates of the primary efficacy endpoint (HRCVdeath/MI/stroke=0.78, 95% CI 0.64-0.95 and HRCVdeath/MI/stroke=0.87, 95% CI 0.69-1.10, respectively; P-int=0.48) and higher rates of the primary safety endpoint (HRTIMI major bleeding=1.40, 95% CI 0.81-2.42 and HRTIMI major bleeding=1.30, 95% CI 0.63-2.68, respectively; P-int=0.84) compared with clopidogrel.
CONCLUSIONS: In TRITON-TIMI 38, the safety/efficacy of prasugrel compared to clopidogrel was directionally consistent regardless of aspirin dose, though only the primary efficacy endpoint achieved statistical significance. There was no clinically meaningful interaction of aspirin with prasugrel, suggesting that previous observations with potent antiplatelet agents indicating differential results are not universal.
CLINICAL TRIAL INFO: http://clinicaltrials.gov/show/NCT00097591; NCT00097591.
PMID: 24140678 [PubMed - as supplied by publisher]