Findings of the STOPDAPT-2 ACS trial presented during a hot line session at the European Society of Cardiology’s 2021 congress (ESC 2021, 27–30 August, virtual), do not support the use of one month of dual antiplatelet therapy (DAPT) in acute coronary syndrome (ACS) patients undergoing stent implantation.
The STOPDAPT-2 trial previously demonstrated that among patients undergoing percutaneous coronary intervention (PCI), one month of DAPT followed by clopidogrel monotherapy resulted in a significantly lower rate of a composite of cardiovascular and bleeding events, compared with 12 months of DAPT with aspirin and clopidogrel. In that trial, 62% of patients had stable coronary artery disease and 38% had ACS.
To generate sufficient statistical power to compare the effect of the two treatments in ACS patients alone, the STOPDAPT-2 ACS trial enrolled 2,988 ACS patients and pooled the results with the 1,148 ACS patients in STOPDAPT-2—for a total of 4,136 patients. Both trials used the same protocol. Participants were randomly assigned in a 1:1 ratio to one-month DAPT followed by clopidogrel monotherapy or 12-month DAPT after PCI with cobalt-chromium everolimus-eluting stents.
The primary outcome was a composite of cardiovascular and bleeding outcomes at one year: death from cardiovascular causes, myocardial infarction, definite stent thrombosis, ischaemic or haemorrhagic stroke, and Thrombolysis in Myocardial Infarction (TIMI) major or minor bleeding.
The two major secondary endpoints were: a cardiovascular composite outcome (death from cardiovascular causes, myocardial infarction, definite stent thrombosis, ischaemic or haemorrhagic stroke); and TIMI major or minor bleeding.
The primary outcome occurred in 65 patients (3.2% one-year cumulative incidence) assigned to one-month DAPT and 58 patients (2.83%) assigned to 12-month DAPT (hazard ratio [HR] 1.14; 95% confidence interval [CI] 0.80–1.62; p=0.06 for noninferiority).
The major secondary cardiovascular outcome occurred in 56 (2.76%) patients in the one-month DAPT group and 38 (1.86%) patients in the 12-month DAPT group (HR 1.50; 95% CI 0.99–2.26). The major secondary bleeding outcome occurred in 11 (0.54%) patients allocated to one-month DAPT and 24 (1.17%) patients allocated to 12-month DAPT (HR 0.46; 95% CI 0.23-0.94).
Study author Hirotoshi Watanabe of Kyoto University, Kyoto, Japan, said: “One-month DAPT and subsequent clopidogrel monotherapy failed to achieve non-inferiority for net clinical benefit compared with standard 12-month DAPT after ACS. There was a trend toward an increase in cardiovascular events despite a reduction in major bleeding events.”