Abstract 15659: Association of Aspirin Dose and Vorapaxar Safety and Efficacy in Non-ST-Segment Elevation Acute Coronary Syndrome Patients in TRACER
Background: In TRACER, 12,944 patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) were randomly assigned to vorapaxar, a novel protease-activated-receptor 1 (PAR-1) antagonist. Vorapaxar nominally reduced the composite of cardiovascular death, myocardial infarction, and stroke but with an increase in bleeding with high use of dual antiplatelet therapy at baseline. Aspirin (ASA) dosing was at the discretion of the physician.
Methods: In this prespecified analysis, the associations of ASA dose at randomization with clinical efficacy and safety of vorapaxar are explored.
Results: Overall, 96% of patients were on ASA at randomization. Of these, 60% were on a low dose (≤100mg), 8.4% were on a medium dose (100-300mg), and 31% were on a high dose (≥300mg). Compared with patients on low-dose ASA, patients on high-dose ASA tended to be heavier; more often had cardiac risk factors (hypertension, diabetes mellitus, hyperlipidemia), prior stroke, and coronary revascularization procedures; and were more often enrolled in North America. Efficacy and safety outcomes in patients assigned vorapaxar compared with placebo and by baseline ASA dose are shown in the Table.
Conclusion: In TRACER, the majority of patients were treated with low-dose ASA. While substantial differences in baseline clinical characteristics based on ASA dosing were observed, the safety and efficacy results observed with vorapaxar by ASA dose were similar to the overall trial results by formal interaction testing. Compared with low-dose ASA, high-dose ASA was associated with consistent trends to a higher hazard of bleeding and less efficacy with vorapaxar compared with placebo.
- © 2012 by American Heart Association, Inc.