WASHINGTON – Guidelines were recently modified to permit shorter duration of dual-antiplatelet therapy (DAPT) after percutaneous coronary intervention, but a series of ongoing trials are evaluating whether DAPT can be abandoned altogether in many if not most percutaneous coronary intervention (PCI) patients, according to a review of this major potential change in direction presented at CRT 2017 sponsored by the Cardiovascular Research Institute at Washington Hospital Center.

“The 1-year duration of dual-antiplatelet therapy post PCI with a drug eluting stent is based on anecdotal historical data,” asserted Patrick W. Serruys, MD, PhD, professor of cardiology, Imperial College, London. Citing several sets of data consistent with the conclusion that single agents provide adequate protection against thrombus formation but reduced risk of bleeding relative to DAPT, he suggested that it is now critical to challenge the old standard.

He is not alone. In addition to the large investigator-initiated 16,000-patient GLOBAL LEADERS trial that he is leading, testing the hypothesis that one antiplatelet drug is enough, at least four other large multicenter studies are pursuing a similar hypothesis.

It has long been understood that greater protection against thrombus formation with more aggressive antiplatelet therapy is purchased with a higher risk of bleeding, but there appears to be a fundamental change in orientation. Several new pieces of evidence, including data showing that shorter duration of DAPT is as good as longer duration, has placed this trade-off in doubt at least over the longer term.

To some degree, the current standard was based on the premise that thrombotic events are more important than bleeding events, according to Usman Baber, MD, assistant professor of cardiology, Icahn School of Medicine at Mount Sinai, New York. He said, “That thought process really dominated thinking for many years, but this is completely unsupported by the data.” Instead, he noted that hazard ratios after thrombotic and bleeding events are almost identical, but the risk of death after bleeding is more persistent, while risk of ischemic events typically diminishes after an initial peak.

The reorientation toward limiting DAPT to the acute risk of thrombosis after PCI is reflected in the recently published 2016 American College of Cardiology/American Heart Association Guideline Update on Duration of Dual Antiplatelet Therapy (Circulation. 2016 Sep 6;134[10]:e123-55). In an analysis of the available data, the authors of those guidelines suggested that shorter duration DAPT after PCI “can be considered in patients at lower ischemic risk and higher bleeding risk,” and the document reviewed recent studies suggesting potential harm from extended DAPT after PCI even if it did not specifically change the standard.

There is no shortage of studies that have attempted to determine the ideal combination and duration of antiplatelet therapies after PCI, but the heterogeneity of study design has prohibited definitive conclusions. In particular, Dr. Serruys suggested that there is no level 1 evidence confirming the value of adding aspirin, which he emphasized has a relatively nonspecific effect, over that of P2Y12 inhibitor alone.

In the design phase of the GLOBAL LEADERS trial, Dr. Serruys recounted, he first argued for a design in which aspirin was eliminated altogether and then for a protocol with only a single week of aspirin, but was met with strong objections each time. In the end, the experimental protocol calls for 1 month of aspirin plus ticagrelor before patients are continued on ticagrelor alone. This is being compared with the current standard, which is aspirin plus ticagrelor or clopidogrel for 12 months followed by another 12 months of aspirin alone.

GLOBAL LEADERS is an all-comers trial in which patients are randomized before PCI. All patients at the 131 participating centers in 18 countries are receiving the same stent (BioMatrix Flex). The primary endpoint is all-cause mortality, and enrollment is completed. The results are expected in November of this year.

There are numerous other studies addressing the same question. Like GLOBAL LEADERS, the TWILIGHT trial is also investigator-initiated and is near the halfway mark for a 9,000-patient enrollment. In this study, patients are being randomized to aspirin plus ticagrelor or ticagrelor alone after they have achieved a successful placement of a drug-eluting stent. This trial, however, is restricted to those with diabetes, chronic kidney disease, or other high-risk features. The primary endpoint is major bleeding. Completion is expected in 2019.

The SMART-CHOICE trial is enrolling roughly 5,000 PCI patients receiving a drug-eluting stent. Patients are being randomized to a P2Y12 antagonist monotherapy plus aspirin or the P2Y12 antagonist alone. The primary endpoint is a composite of major adverse cardiovascular events as well as major bleeding events.

After the STOP DAPT trial showed that 3 months of DAPT after PCI was as safe as prolonged DAPT in patients receiving a everolimus-eluting chromium-cobalt stent (Cardiovasc Interv Ther. 2016;31:196-209), the same group of Japanese investigators conceived the STOP-DAPT2 trial. In this trial, 3,000 patients are being randomized a standard DAPT or clopidogrel monotherapy beginning 1 month after PCI. The primary outcome is similar to that of SMART-CHOICE.

In yet another trial cited by Dr. Serruys, patients will receive DAPT only if the PCI outcome is considered suboptimal. For those judged to have a good result, patients will receive ticagrelor alone. Outcomes at the end of 1 year will be monitored.

The movement toward antiplatelet monotherapy is driven by recognition that “the need to mitigate the risk of bleeding is an important as the need to mitigate thrombosis,” Dr. Baber explained. Like Dr. Serruys, he believes it is important to challenge the standard.

“By testing single, specific, and potent antiplatelet therapy and getting rid of the old and nonspecific platelet drug called acetylsalicylic acid, we may be able to simplify risk management after PCI,” agreed Dr. Serruys. If, as expected, the GLOBAL LEADERS and other monotherapy antiplatelet trials meet their endpoints, it will mean a major evolution in postprocedural risk management.

Dr. Serruys reported no financial relationships to disclose.

Prolonged dual-antiplatelet therapy after PCI challenged