DAPT for 1 Month Falls Short in Acute Coronary Syndrome

The 1-month dual antiplatelet (DAPT) strategy used in the STOPDAPT-2 acute coronary syndrome (ACS) trial failed to match the safety and efficacy outcomes of the original STOPDAPT-2 study.

For a composite primary endpoint of cardiovascular (CV) death, myocardial infarction, stroke, definite stent thrombosis, or major or minor bleeding in ACS patients, the cumulative event rate was 3.2% in the 1-month DAPT group and 2.83% in the 12-month group, for a difference that was not statistically different (HR 1.15, 95% CI 0.80-1.62), reported Hirotoshi Watanabe, MD, of Kyoto University in Japan.

Also, the MI rate was significantly higher with 1-month DAPT (1.59% vs 0.85% at 12 months; HR 1.91, 95% CI 1.06-3.44), although the cumulative rates of Thrombolysis in Myocardial Infarction (TIMI) major and minor bleeding were significantly lower (0.54% vs 1.17% at 12 months; HR 0.46, 95% CI 0.23-0.94), he said in a presentation at the European Society of Cardiology (ESC) virtual meeting.

The original STOPDAPT-2 trial showed both non-inferiority and superiority of 1-month DAPT followed by clopidogrel (Plavix) monotherapy through 1 year against 12 months of DAPT post-percutaneous coronary intervention. In the first trial, only 38% of the patients had ACS; all received a permanent-polymer, cobalt-chromium, everolimus-eluting stent (Xience).

Watanabe explained that the prespecified upper limit of the confidence interval was 1.50, but the interval found in the STOPDAPT-2 ACS fell outside that limit, so non-inferiority could not be shown.

In addition, he noted that there “was a trend toward an increase in cardiovascular events despite a reduction in major bleeding events.”

The trial’s findings were very different than those from the MASTER DAPT study, also presented at the meeting. ESC press conference moderator Carlos Aguiar, MD, of Hospital Santa Cruz in Portugal, acknowledged that the conflicting results could leave doctors and patients with whiplash. But he stressed that the patient populations in MASTER DAPT and STOPDAPT-2 ACS were very different.

For instance, STOPDAPT-2 did not include patients taking oral anticoagulation while MASTER DAPT did. Also, MASTER DAPT patients received a stent with a bioresorbable polymer (Ultimaster), and because it was the only stent used in that study, the findings cannot be applied to other devices, Aguiar told MedPage Today at the time of the study presentation.

Aguiar said that the STOPDAPT-2 ACS findings would not change current practice, but that the study “still confirms, through some data that is prospectively and adequately collected, that we do see higher rates of bleeding with prolonged DAPT.”

“Bleeding is a factor we need to continue to consider when deciding how long DAPT should be continued in patients,” he said.

STOPDAPT-2 ACS enrolled 2,988 patients with ACS and pooled the results with those from patients with ACS in STOPDAPT-2, for a total study population of 4,136 patients. Both trials used the same protocol.

Watanabe also noted that major secondary CV outcomes occurred in 2.76% of patients in the 1-month DAPT group and 1.86% patients in the 12-month group (HR 1.50, 95% CI 0.99-2.26). Major secondary bleeding occurred in 0.54% and 1.17%, respectively (HR 0.46, 95% CI 0.23-0.94), indicating that bleeding remains a problem with longer-term DAPT, he reiterated.

Sarah Clarke, MD, of Royal Papworth Hospital in Cambridge, England told MedPage Today that STOPDAPT-2 ACS demonstrated “no benefit in stopping [DAPT] early and using clopidogrel as the single agent.” But she added that “we need more data before we can really be clear…there are other issues to [consider], such as the type of stent used, the type of lesions being stented, cost, and other procedural issues … it’s not a black-or-white decision.”