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Long-Term Dual Antiplatelet Therapy for Patients With Previous MI
Study Questions:
What are the cardiovascular benefits and risks of dual antiplatelet therapy (DAPT) beyond 1 year for secondary prevention in high-risk patients with a prior myocardial infarction (MI)?
Methods:
The investigators 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 MI. Data from each trial were considered as per the intention-to-treat principle with pooled summary risk ratio (RR) and 95% confidence interval (CI) derived using a random effects meta-analysis model with weighting based on inverse variance.
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%; RR, 0.78; 95% CI, 0.67-0.90; p = 0.001) and reduced cardiovascular death (2.3 vs. 2.6%; RR, 0.85; 95% CI, 0.74-0.98; p = 0.03), with no increase in noncardiovascular death (RR, 1.05; 95% CI, 0.88-1.24; p = 0.61). The resultant effect on all-cause mortality was an RR of 0.92 (95% CI, 0.83-1.03; p = 0.13). Extended DAPT also reduced MI (RR, 0.70; 95% CI, 0.55-0.88; p = 0.003), stroke (RR, 0.81; 95% CI, 0.68-0.97; p = 0.02), and stent thrombosis (RR, 0.50; 95% CI, 0.28-0.89; p = 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 = 0.004), but not fatal bleeding (0.14 vs. 0.17%; RR, 0.91; 95% CI, 0.53-1.58; p = 0.75).
Conclusions:
The authors concluded that compared with aspirin alone, DAPT beyond 1 year among stabilized high-risk patients with prior MI decreases ischemic events, including significant reductions in the individual endpoints of cardiovascular death, recurrent MI, and stroke.
Perspective:
This meta-analysis of high-risk patients stabilized following an MI found that, overall compared with aspirin alone, extended DAPT beyond 1 year resulted in a 22% relative and 1.1% absolute risk reduction for major adverse cardiovascular events over a mean 31 months of follow-up. There was, however, a 0.8% absolute increase in the risk of major bleeding. It should be noted that this analysis pooled trials with heterogeneous populations that varied in treatment strategy, study design, intended primary outcome, and major bleeding definitions. Overall, it appears that in high-risk patients with prior MI who are at low risk of bleeding, continuation of DAPT beyond a year may offer a substantial reduction in adverse cardiovascular outcomes.
Keywords: Aspirin, Hemorrhage, Myocardial Infarction, Platelet Aggregation Inhibitors, Risk, Risk Assessment, Secondary Prevention, Stents, Stroke, Thrombosis, ESC Congress
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