P2Y12 Inhibitor Monotherapy with Clopidogrel versus Ticagrelor in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Background: P2Y12 inhibitor monotherapy is an alternative antiplatelet strategy in patients undergoing percutaneous coronary intervention (PCI). However, the ideal P2Y12 inhibitor for monotherapy is unclear. Methods and Results: We performed a multicenter, retrospective, observational study to compare the efficacy and safety of monotherapy with clopidogrel versus ticagrelor in patients with acute coronary syndrome (ACS) undergoing PCI. From 1 January 2014 to 31 December 2018, 610 patients with ACS who received P2Y12 monotherapy with either clopidogrel (n = 369) or ticagrelor (n = 241) after aspirin was discontinued prematurely were included. Inverse probability of treatment weighting was used to balance covariates between the groups. The primary endpoint was the composite of all-cause mortality, recurrent ACS or unplanned revascularization, and stroke within 12 months after discharge. Overall, 84 patients reached the primary endpoint, with 57 (15.5%) in the clopidogrel group and 27 (11.2%) in the ticagrelor group. Multivariate adjustment in Cox proportional-hazards models revealed a lower risk of the primary endpoint with ticagrelor than with clopidogrel (adjusted hazard ratio (aHR): 0.67, 95% confidence interval (CI): 0.49–0.93). Ticagrelor significantly reduced the risk of recurrent ACS or unplanned revascularization (aHR: 0.46, 95% CI: 0.28–0.75). No significant difference in all-cause mortality and major bleeding events was observed between the 2 groups. Conclusions: Among patients with ACS undergoing PCI who cannot complete course of dual antiplatelet therapy, a significantly lower risk of cardiovascular events was associated with ticagrelor monotherapy than with clopidogrel monotherapy. The major bleeding risk was similar in both the groups.