Nonadherence to ticagrelor versus clopidogrel and clinical outcomes in patients with ACS. Results from the CREA-ARIAM registry.

Introduction And Objectives: Prior studies have not determined whether the effect of dual antiplatelet therapy (DAPT) cessation on the subsequent risk of major adverse cardiac events (MACE) varies by the choice of P2Y-inhibitor after acute coronary syndrome (ACS).

Methods: We performed a prespecified subanalysis of a multicenter, prospective registry of ACS patients discharged on ticagrelor or clopidogrel between 2015 and2019. Nonadherence to DAPT was categorized as physician-guided discontinuation and disruption due to adverse effects, nonadherence, or bleeding. The association between DAPT cessation and 1-year MACE was analyzed using multivariate time-updated Cox models with inverse probability of censoring weighted estimators.

Results: Out of 2180 patients, 174 (8.3%) prematurely discontinued DAPT (physician-guided, n=126; disruption, n=48). Nonadherent patients were older and had more comorbidities than those on DAPT. Compared with physician-guided discontinuation, disruption occurred earlier after discharge and was more frequent with ticagrelor than with clopidogrel. In time-varying analysis, DAPT cessation was associated with an increased risk of MACE ( HR, 1.32, 95%CI, 1.10-1.76), largely driven by disruption ( HR, 1.47, 95%CI, 1.22-1.73). There was an exponential increase in MACE risk after DAPT cessation within 90 days after ACS, especially after disruption of ticagrelor compared with clopidogrel (P<.001). After adjustment for DAPT duration, this interaction was not statistically significant on the additive scale (relative excess risk due to interaction 0.12, 95%CI,-0.99-1.24).

Conclusions: In this all-comers registry, 1 in 12 patients prematurely discontinued DAPT within 1 year after ACS. Compared with physician-recommended discontinuation, disruption resulted in a significantly higher risk of MACE. After adjustment for DAPT duration, this association was not moderated by the choice of P2Y-inhibitor. Clinical trial registered at ClinicalTrials.gov (Identifier: NCT02500290).