One month of dual antiplatelet therapy followed by 11 months of clopidogrel monotherapy failed to prove noninferiority to 12 unbroken months of DAPT for net clinical benefit in a multicenter Japanese trial that randomized more than 4,000 patients who underwent percutaneous coronary intervention (PCI) after a recent acute coronary syndrome episode.
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The outcomes showed that while truncating DAPT duration could, as expected, cut major bleeding episodes roughly in half, it also led to a significant near doubling of myocardial infarction and showed a strong trend toward also increasing a composite tally of several types of ischemic events. These data were reported this week by Hirotoshi Watanabe, MD, PhD, at the virtual annual congress of the European Society of Cardiology. All study patients had undergone PCI with cobalt-chromium everolimus-eluting (CCEE) coronary stents (Xience).
These findings from the STOPDAPT-2 ACS trial highlighted the limits of minimizing DAPT after PCI in patients at high ischemic risk, such as after an acute coronary syndrome (ACS) event.
It also was a counterpoint to a somewhat similar study also reported at the congress, MASTER DAPT, which showed that 1 month of DAPT was noninferior to 3 or more months of DAPT for net clinical benefit in a distinctly different population of patients undergoing PCI (and using a different type of coronary stent) – those at high bleeding risk and with only about half the patients having had a recent ACS.
The results of STOPDAPT-2 ACS “do not support use of 1 month of DAPT followed by P2Y12 inhibitor monotherapy with clopidogrel compared with standard DAPT,” commented Robert A. Byrne, MBBCh, PhD, designated discussant for the report and professor at the RCSI University of Medicine and Health Sciences in Dublin.
“Although major bleeding was significantly reduced with this approach, there appeared to be a significant increase in adverse ischemic events, and there was a clear signal in relation to overall mortality, the ultimate arbiter of net clinical benefit,” added Dr. Byrne, who is also director of cardiology at Mater Private Hospital in Dublin.
He suggested that a mechanistic explanation for the signal of harm seem in STOPDAPT-2 ACS was the relatively low potency of clopidogrel (Plavix) as an antiplatelet agent, compared with other P2Y12 inhibitors such as prasugrel (Effient) and ticagrelor (Brilinta), as well as the genetically driven variability in response to clopidogrel that’s also absent with alternative agents.
These between-agent differences are of “particular clinical relevance in the early aftermath of an ACS event,” Dr. Byrne said.
12-month DAPT remains standard for PCI patients with recent ACS
The totality of clinical evidence “continues to support a standard 12-month duration of DAPT – using aspirin and either prasugrel or ticagrelor – as the preferred default approach,” Dr. Byrne concluded.
He acknowledged that an abbreviated duration of DAPT followed by P2Y12 inhibitor monotherapy “might be considered as an alternative.” In patients following an ACS event who do not have high risk for bleeding, he said, the minimum duration of DAPT should be at least 3 months and with preferential use of a more potent P2Y12 inhibitor.
Twelve months of DAPT treatment with aspirin and a P2Y12 inhibitor for patients following PCI “remains the standard of care in guidelines,” noted Marco Roffi, MD, a second discussant at the congress. But several questions remain, he added, such as which P2Y12 inhibitors work best and whether DAPT can be less than 12 months.
“The investigators [for STOPDAPT-2 ACS] pushed these questions to the limit with 1 month of DAPT and clopidogrel monotherapy,” said Dr. Roffi, professor and director of interventional cardiology at University Hospital, Geneva.
“This was a risky bet, and the investigators lost by not proving noninferiority and with excess ischemic events,” he commented.