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AMSTERDAM -- Two trials from Asia weighed in on reducing components and duration of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) but with questionable applicability to Western practice.

Both trials were presented at hotline sessions at the European Society of Cardiology (ESC) Congress.

In the STOPDAPT-3 trial, relying on prasugrel (Effient) alone after PCI didn't significantly hurt 30-day composite risk of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischemic stroke compared with aspirin plus prasugrel (4.12% vs 3.69%; HR 1.12, 95% CI 0.87-1.45).

But neither was there a significant advantage in reducing BARC 3 or 5 bleeding risk (4.71% vs 4.47%, respectively, P=0.66 for superiority), Masahiro Natsuaki, MD, of Saga University in Japan, reported here.

And there was a significant 3.4-fold higher risk of subacute definite or probable stent thrombosis with the aspirin-free approach (0.58% vs 0.17%) along with an 83% relative increase in unplanned coronary revascularization atop nonsignificant trends in a similar direction for other thrombotic and mortality endpoints.

"DAPT with aspirin and a P2Y12 inhibitor would still remain the standard strategy at least for 1 month after PCI," Natsuaki concluded.

While prasugrel is uncommonly used in this setting in the U.S. and especially at the 3.75-mg daily dose used in the trial rather than the usual 10 mg, there is potential relevance for U.S. practice, commented Jacqueline Tamis-Holland, MD, of the Cleveland Clinic, who was chair of the American Heart Association/American College of Cardiology revascularization guidelines writing committee.

"This is sort of consistent with what we saw in the triple therapy versus the double therapy trials, where you drop the aspirin if you're giving anticoagulation and you see this early rate of stent thrombosis," she told 番茄社区app. "I'm going to be more cautious about continuing that aspirin in the early days after PCI, particularly in my ACS [acute coronary syndrome] patients."

But there's still room for trials of dropping aspirin, perhaps after an early post-PCI load, she suggested. "I don't think we should close the book on dropping aspirin."

The trial randomized 6,000 patients in Japan with ACS or high bleeding risk undergoing PCI with an everolimus-eluting stent.

In the OPT-BIRISK trial, switching to clopidogrel monotherapy after 9 to 12 months of DAPT was better for bleeding risk without an increase in ischemic risk for stented ACS patients at both high bleeding and ischemic risk.

The abbreviated aspirin regimen reduced clinically relevant bleeding risk -- defined as BARC 2, 3, or 5 -- by 25% over 9 months (2.5% vs 3.3%, P=0.03), reported Yaling Han, MD, of Shenyang Northern Hospital in China, and a past president of the Chinese Society of Cardiology.

Composite risk of all-cause mortality, myocardial infarction, stroke, or clinically driven revascularization was actually lower in the group that dropped aspirin as well (2.6% vs 3.5%; HR 0.74, 95% CI 0.57-0.96, P=0.02).

Individual components as well as more serious BARC 3 and 5 bleeding events all favored the clopidogrel monotherapy arm.

The trial included 7,758 ACS patients at 101 Chinese centers from February 2018 through December 2020. After 9 to 12 months of DAPT post-PCI, the participants were randomized to stay on clopidogrel and aspirin or switch to clopidogrel and placebo in a double-blind fashion for 9 months. Thereafter, both groups got aspirin alone for 3 months.

While both trials were important in adding large datasets to the ongoing debate about when and what to de-escalate in the post-PCI antithrombotic regimen, Renato Lopes, MD, PhD, of Duke University Medical Center in Durham, North Carolina, who served as the study discussant at the session, argued that the findings might not be generalizable.

There are many differences in Asian versus Western populations, including tolerance of and care-seeking for bleeding events, platelet-impacting genetics, diet, and ischemic event and myocardial infarction characteristics, he said.

"They add some more information, but at the same time, there are so many limitations that are not applicable to the rest of the world," he told 番茄社区app.