Introduction <p>Antiplatelet therapy with low-dose aspirin, alone or as dual antiplatelet therapy (DAPT) with a P2Y₁₂ inhibitor, is used in secondary prevention following myocardial infarction (MI). However, the optimal duration of DAPT is unknown.</p> Methods <p>This cohort study performed in the French nationwide claims database compared 3-year outcomes between DAPT and low-dose aspirin alone pursued beyond 1 year after MI. All adults discharged from hospital following MI in 2013–2014, and who survived ≥ 1 year under DAPT, without rehospitalization for acute coronary syndrome or major bleeding were enrolled (<i>N</i> = 51,468). The primary outcome was a composite of MI, stroke, major bleeding, or all-cause death during the 3 years following the index date (defined as 365 days after MI). Secondary outcomes were a composite of MI, stroke, and all-cause death, and each component of the primary composite. DAPT and low-dose aspirin exposure periods were analyzed as time-dependent variables and compared using hazard ratios (HR) from Cox proportional hazard or Fine–Gray competing risks models, adjusted using a high-dimensional disease risk score.</p> Results <p>The 3-year cumulative follow-up duration was 93,398 person-years (DAPT exposure: 26,223 person-years; low-dose aspirin exposure: 67,175 person-years). HRs for DAPT versus low-dose aspirin were 0.93 (0.85–1.03) for the primary composite outcome, 0.93 (0.84–1.03) for the secondary composite outcome, 1.04 (0.87–1.25) for MI, 0.91 (0.70–1.17) for stroke, 1.19 (0.88–1.60) for major bleeding, and 0.94 (0.83–1.07) for death.</p> Conclusions <p>This national cohort study did not find a significant benefit of continued DAPT beyond 1 year after MI compared with low-dose aspirin.</p> Registration <p>This study was registered with the European Medicines Agency EUPASS registry (<a href="https://catalogues.ema.europa.eu/catalogue-rwd-studies">https://catalogues.ema.europa.eu/catalogue-rwd-studies</a>; registration no. EUPAS29177).</p> Graphical Abstract <p></p>