Age, outcomes, and treatment effects of fibrinolytic and antithrombotic combinations: Findings from Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT)-3 and ASSENT-3 PLUS

Background Elderly patients with acute myocardial infarction are at particularly high risk for death and bleeding complications. The efficacy and safety of antithrombotic strategies in these patients remain unclear. Methods To provide more insight into the risk and benefit of antithrombotic strategies in the elderly, we examined patients from the ASSENT-3 and ASSENT-3 PLUS trials with STEMI who were treated with tenecteplase (TNK) and unfractionated heparin (UFH) or enoxaparin, or half-dose TNK with abciximab and reduced-dose UFH. Results Older patients had a higher risk profile, and lower use of concomitant therapies and revascularization procedures. We found an interaction between age and treatment effect for the efficacy end point (P = .0007) and the efficacy plus safety end point (P < .0001). Younger patients (<65 years) had a lower risk of the composite efficacy plus safety end point with enoxaparin (relative risk [RR] 0.84, 95% CI 0.74-0.94) or abciximab (RR 0.79, 95% CI 0.69-0.90) compared with UFH. In patients >65 years of age, the benefit of enoxaparin appeared to be offset by an increased risk of bleeding complications. The risk of the efficacy plus safety end point tended to be higher in elderly patients receiving abciximab and half-dose TNK (RR 1.18, 95% CI 0.91-1.51 for 76-85 years of age and RR 1.48, 95% CI 0.88-2.49 for >85 years of age). Conclusions Although TNK with either enoxaparin or abciximab appeared to be more effective than with standard UHF in younger patients, these combinations tended to be less effective and even may be unsafe in the elderly. Development of new combination strategies and dosing schemes of fibrinolytics and antithrombotics with improved efficacy and safety in the elderly remains a high priority.