Non-inferiority criteria not met for one-month DAPT after stenting in ACS

STOPDAPT-2 ACS: one-month dual antiplatelet therapy followed by clopidogrel monotherapy in acute coronary syndrome

Presented at the ESC congress 2021 by: Hirotoshi Watanabe, MD, PhD Kyoto, Japan

Introduction and methods

The STOPDAPT-2 ACS trial was designed to examine efficacy and safety of 1-month DAPT followed by clopidogrel monotherapy compared with standard 12-months DAPT with aspirin and clopidogrel after implantation of CoCr-EES stent in ACS patients. This trial was a multicenter, open-label RCT in Japan. The study protocol was the same as of STOPDAPT-2 but now exclusively with ACS patients. Primary endpoint was the net outcome of CV events (composite of CV death, MI, stent thrombosis and stroke) and bleeding (TIMI major and minor).

A total of 4169 ACS patients (including 1161 from previous STOPDAPT-2 trial) were randomized to 1-month DAPT or 12-month DAPT.

Main results

• Incidence of the primary endpoint was 3.20% in the 1-month DAPT group and 2.83% in the 12-month DAPT group, resulting in HR 1.14, 95%CI: 0.80-1.62. The upper limit of 95%CI was above the margin for non-inferiority, so the criteria for non-inferiority for 1-month DAPT were not met.
• Major secondary CV endpoint, CV death, definite stent thrombosis and stroke were not different between the 2 groups. Rate of MI appeared to be higher in the 1-month DAPT group than in the 12-month DAPT (HR 1.91, 95%CI: 1.06-3.44) and bleeding lower in the 1-month DAPT group (HR 0.46, 95%CI:0.23-0.94).
• When comparing the results to those of the previous STOPDAPT-2 trial, there was inconsistency for the primary endpoint (in STOPDAPT-2 the HR was 0.64, 95%CI:0.42-0.98), and for the major secondary CV endpoint (in STOPDAPT-2 the HR was 0.79, 95%CI:0.49-1.29 and in the present study the HR was 1.50, 95%CI: 0.99-2.26). Bleeding outcomes were similar with a reduction in bleeding with one-month DAPT in both trials.

Conclusion

1-Month DAPT followed by clopidogrel monotherapy was not noninferior to 12-months DAPT with regard to net benefit in ACS patients after stent implantation.

Prof. Watanabe said that in ACS patients clopidogrel monotherapy may not be the optimal medication, but more potent P2Y12 inhibitors, such as prasugrel or ticagrelor, may have to be used as monotherapy after DAPT discontinuation.

- Our reporting is based on the information provided at the ESC Congress -