Long-term dual antiplatelet therapy for secondary prevention of cardiovascular events in the subgroup of patients with previous myocardial infarction

Aims Recent trials have examined the effect of prolonged dual antiplatelet therapy (DAPT) in a variety of patient populations, with heterogeneous results regarding benefit and safety, specifically with regard to cardiovascular and non-cardiovascular mortality.We performed a meta-analysis of randomized trials comparing more than a year of DAPT with aspirin alone in high-risk patients with a history of prior myocardial infarction (MI).
Methods and results A total of 33 435 patients were followed over a mean 31 months among one trial of patients with prior MI (63.3% of total) and five trials with a subgroup of patients that presented with, or had a history of, a prior MI (36.7% of total). Extended DAPT decreased the risk of major adverse cardiovascular events compared with aspirin alone (6.4 vs. 7.5%; risk ratio, RR 0.78, 95% confidence intervals, CI, 0.67–0.90; P ¼ 0.001) and reduced cardiovascular death (2.3 vs. 2.6%; RR 0.85, 95% CI 0.74–0.98; P ¼ 0.03), with no increase in non-cardiovascular death (RR 1.03, 95% CI 0.86–1.23; P ¼ 0.76). The resultant effect on all-cause mortality was an RR of 0.92 (95% CI 0.83–1.03; P ¼ 0.13). Extended DAPT also reduced MI (RR 0.70, 95% CI 0.55–0.88; P ¼ 0.003), stroke (RR 0.81, 95% CI 0.68–0.97; P ¼ 0.02), and stent thrombosis (RR 0.50, 95% CI 0.28–0.89; P ¼ 0.02). There was an increased risk of major bleeding (1.85 vs. 1.09%; RR 1.73, 95% CI 1.19–2.50; P ¼ 0.004) but not fatal bleeding (0.14 vs. 0.17%; RR 0.91, 95% CI 0.53–1.58; P ¼ 0.75).
Conclusion Compared with aspirin alone, DAPT beyond 1 year among stabilized high-risk patients with prior MI decreases ischaemic events, including significant reductions in the individual endpoints of cardiovascular death, recurrent MI, and stroke. Dual antiplatelet therapy beyond 1 year increases major bleeding, but not fatal bleeding or non-cardiovascular death.