P2Y12 inhibitor monotherapy after short DAPT in acute coronary syndrome: a systematic review and meta-analysis

Background: P2Y12 inhibitor monotherapy after a short course of dual antiplatelet therapy (DAPT) may balance ischaemic and bleeding risks in patients with acute coronary syndrome (ACS). However, it remains uncertain how different P2Y12 inhibitors used as monotherapy affect outcomes. Methods and results: Randomized controlled trials comparing P2Y12 inhibitor monotherapy after a short course of DAPT (≤3 months) vs. 12-month DAPT in ACS were included. The primary endpoint was major adverse cardiovascular events (MACE). All analyses included an interaction term for the P2Y12 inhibitor used as monotherapy. Trial sequential analyses were run to explore whether the effect estimate of each outcome may be affected by further studies. Seven trials encompassing 27 284 ACS patients were included. Compared with 12-month DAPT, P2Y12 inhibitor monotherapy after a short course of DAPT was associated with no difference in MACE [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.76-1.12] and a significant reduction in net adverse clinical events (NACE) (OR 0.75; 95% CI 0.60-0.94), any bleeding (OR 0.54, 95% CI 0.43-0.66), and major bleeding (OR 0.47, 95% CI 0.37-0.60). Significant interactions for subgroup difference between ticagrelor and clopidogrel monotherapy were found for MACE (Pint = 0.016), all-cause death (Pint = 0.042), NACE (Pint = 0.018), and myocardial infarction (Pint = 0.028). Trial sequential analysis showed conclusive evidence of improved NACE with ticagrelor, but not with clopidogrel monotherapy, compared with standard DAPT. Conclusions: In patients with ACS, P2Y12 inhibitor monotherapy after short DAPT halves bleeding without increasing ischaemic events compared with standard DAPT. Ticagrelor, but not clopidogrel monotherapy, reduced MACE, NACE, and mortality compared with standard DAPT, supporting its use after aspirin discontinuation.