Dropping Aspirin After PCI: New Studies Published

July 01, 2019

Two new Asian studies have shown that short durations of dual antiplatelet therapy (DAPT) followed by longer treatment with P2Y12 inhibitor monotherapy alone may be a safe and effective regimen for patients undergoing percutaneous coronary intervention (PCI) with second-generation drug-eluting stents.

The studies — the STOPDAPT-2 trial from Japan and the SMART-CHOICE trial from Korea — were published in JAMA on June 25.

They were first presented at the American College of Cardiology meeting earlier this year and were reported by theheart.org | Medscape Cardiology at that time.

In both studies, shortening the duration of DAPT and continuing with P2Y12 monotherapy alone reduced bleeding complications without increasing risk for death or ischemic events.

They thus provide more evidence that long-term DAPT may not be necessary after PCI with contemporary stents and that dropping aspirin may be a better approach than discontinuing the P2Y12 antiplatelet agent.

In an editorial that accompanies the JAMA publications, Khaled M. Ziada, MD, and David J. Moliterno, MD, University of Kentucky, Lexington, say the conclusions of both reports are "welcome and important news."

But they add, "While it is possible to shorten the DAPT duration in selected cases, the evidence is not sufficient to fully cut the cord with traditional DAPT or aspirin monotherapy — not for all patients and not just yet."

The Japanese STOPDAPT-2 trial involved 3045 patients who underwent PCI at 90 hospitals in Japan. They were randomly assigned to receive either to 1 month of DAPT followed by clopidogrel (Plavix, Sanofi Aventis) monotherapy or to 12 months of DAPT with aspirin and clopidogrel.

Results showed that 1-month DAPT was both noninferior and superior to 12-month DAPT for the primary endpoint — a composite of cardiovascular death, myocardial infarction (MI), ischemic or hemorrhagic stroke, definite stent thrombosis, or major or minor bleeding at 12 months. This endpoint occurred in 2.36% of patients who received 1-month DAPT and in 3.70% of those who received 12-month DAPT (P for superiority = .04).

The major secondary cardiovascular endpoint, a composite of cardiovascular death, MI, ischemic or hemorrhagic stroke, or definite stent thrombosis, occurred in 1.96% of the 1-month DAPT group and 2.51% of the 12-month DAPT group, meeting criteria for noninferiority but not for superiority.

The major secondary bleeding endpoint — major or minor bleeding — occurred in 0.41% of those who received 1-month DAPT and 1.54% of those who received 12-month DAPT, showing clear superiority (P = .004).

In the Korean SMART-CHOICE trial, 2993 patients undergoing PCI with drug-eluting stents were randomly assigned to receive either aspirin plus a P2Y12 inhibitor for 3 months and thereafter P2Y12 inhibitor alone or DAPT for 12 months.

The primary endpoint was major adverse cardiac and cerebrovascular events, a composite of all-cause death, MI, or stroke at 12 months. This occurred in 2.9% of the P2Y12 inhibitor monotherapy group and in 2.5% of the DAPT group, fulfilling noninferiority criteria (P = .007).

The rate of bleeding (Bleeding Academic Research Consortium type 2 to 5) was significantly lower in the P2Y12 inhibitor monotherapy group than in the DAPT group (2.0% vs 3.4%; hazard ratio, 0.58; P = .02).

In their editorial, Ziada and Moliterno point out some limitations of the studies. These include the facts that in both studies, rates of ischemic event were relatively low and that 60% of the patients had stable coronary disease, leading to questions as to whether the results could be extrapolated to higher-risk patients,

"There is reasonable evidence that shorter DAPT is safer in stable patients but may not be as safe in patients with acute coronary syndrome, those with complex coronary anatomy, or those with poor response to clopidogrel," they write.

They also note that both studies were conducted in East Asian populations, which have distinct phenotypic and genotypic features that influence risk for adverse outcomes and response to pharmacotherapeutics.

For example, for the patients in these studies, body mass indexes were lower compared to US patients. Also, clopidogrel loss-of-function alleles are more prevalent in East Asian populations.

In addition, for a high proportion of drug-eluting stent procedures performed in Japan and Korea, intravascular imaging is used to optimize outcomes; such technology is used in a minority of procedures in Europe and North America.

"Such observations warrant caution before extending the conclusions of these studies to patients of other ethnicities or in regions where interventional practices are different," the editorialists state.

They note that more information will come from the TWILIGHT trial currently underway in 9000 high-risk patients who were randomly assigned to receive 1 month of DAPT that includes ticagrelor (Brilenta, AstraZeneca) followed by ticagrelor monotherapy compared with 12 months of DAPT.

The STOPDAPT-2 study was funded by Abbott Vascular. Several coauthors have received personal fees from Abbott Vascular Japan. The SMART-CHOICE study was supported by grants from the Korean Society of Interventional Cardiology, Abbott Vascular, Biotronik, and Boston Scientific. Two of the coauthors have received grants/speakers fees from the three companies. Moliterno has received grants from AstraZeneca.

JAMA. Published online June 25. STOPDAPT-2, abstract; SMART-CHOICE; abstract; Editorial

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