DENVER (FRONTLINE MEDICAL NEWS) – Six months of dual-antiplatelet therapy proved equivalent in terms of safety, efficacy, and bleeding risk to the guideline-recommended standard 12 months in ST-elevation MI patients after primary PCI with a second-generation drug-eluting stent in the randomized DAPT-STEMI trial.

“This trial, for the first time, showed that in the modern DES [drug-eluting stent] era, event-free STEMI patients do not benefit from a prolonged DAPT beyond 6 months, as currently recommended, and sets the stage for further dedicated research in this important topic,” Elvin Kedhi, MD, PhD , declared in presenting the DAPT-STEMI results at the Transcatheter Cardiovascular Therapeutics annual educational meeting.

DAPT-STEMI was a prospective randomized international study that enrolled 1,100 STEMI patients who underwent primary PCI with the second-generation Resolute Integrity zotarolimus-eluting stent and were placed on 6 months of DAPT. After that truncated period of DAPT, patients who had not had an ischemic or bleeding event or other reason for ineligibility during the initial 6 months were then randomized to continue DAPT for another 6 months in accord with current guidelines or were switched to single-antiplatelet therapy (SAPT) with aspirin.

The final analysis took place at 24 months post STEMI; that is, 18 months post randomization. Among the 861 completers, the composite primary outcome of death, MI, revascularization, stroke, and major bleeding during months 6-24 occurred in 4.8% of the SAPT group, a 27% relative risk reduction compared with the 6.6% rate in the DAPT group. Thus, 6 months of DAPT met the prespecified endpoint of noninferiority compared to the standard 12 months of DAPT, reported Dr. Kedhi, head of interventional cardiology and clinical research and innovation at the Isala Heart Center in Zwolle, The Netherlands.

The secondary composite endpoint of death, MI, stroke, stent thrombosis, or TIMI major bleeding occurred in 3.2% of the SAPT group and 4.3% of the DAPT group, for a 25% relative risk reduction.

All individual components of the composite endpoints occurred at the same or lower rate in the SAPT group compared with the DAPT arm, he noted at the meeting, which was sponsored by the Cardiovascular Research Foundation.

At a press conference where Dr. Kedhi presented the DAPT-STEMI results, discussant Dean J. Kereiakes, MD , explained why he didn’t find the study results surprising.

“The second- and third-generation stents are better. They’re safer. And in STEMI, where you may have multicentric disease and an acute systemic inflammatory process, the other treatments that we’re giving – statins, ACE inhibitors, etc. – are also preventing ischemic events,” said Dr. Kereiakes, medical director of the Christ Hospital Heart and Vascular Center in Cincinnati and professor of clinical medicine at Ohio State University, Columbus.

Press conference moderator Gary S. Mintz, MD, put the DAPT-STEMI findings in perspective: “The need for DAPT has decreased along with all the stent-related complications. There’s always been a greater focus on DAPT for preventing events and a relatively lesser focus on the adverse consequences of DAPT. And anybody who’s a clinician who takes care of patients knows that drug-related bleeding after stent implantation is not a trivial occurrence,” observed Dr. Mintz, chief medical officer at the Cardiovascular Research Foundation in Washington.

DAPT-STEMI isn’t the final word on DAPT duration

At a late-breaking clinical trials session, comoderator Eric D. Peterson, MD , noted that in earlier megatrials such as PEGASUS, DAPT, and PLATO, there were signals that extending DAPT beyond 12 months might be even more beneficial than the guideline-recommended 12 months.

“It seems somewhat counterintuitive that now you have better results with less. Any speculation as to why?” asked Dr. Peterson, executive director of the Duke Clinical Research Institute and professor of medicine at Duke University in Durham, N.C.

“It’s true that DAPT reduces the general risk of thromboembolic events, but it does so at a relative risk reduction rate of about 20%, while it augments the bleeding risk by over 200%. And ask yourself, what is the benefit of this 6 months of extra DAPT on the lifelong process of atherosclerosis? It’s almost invisible,” Dr. Kedhi explained.

Dmitriy N. Feldman, MD , of Cornell University in New York, was one of several discussants to note that DAPT-STEMI was statistically underpowered to reach definitive conclusions. But he nonetheless found the results encouraging.

“It’s very reassuring that the stent thrombosis rates are quite low: 0.7% and 0.9%. And with this DES system and 42% of patients receiving clopidogrel rather than ticagrelor or prasugrel we still see low event rates. This is a very select group – patients had to tolerate the first 6 months of DAPT without MACE events or bleeding. But it is reassuring that in patients who are able to do well at 6 months, this is an option,” the interventional cardiologist said.

Session moderator Gregg W. Stone, MD , called DAPT-STEMI “hypothesis-generating” in light of its limited size and statistical power.

“At least it raises the concept of shorter-duration DAPT, whereas I’d say before today it was not a concept. We were always talking about prolonging DAPT in the highest-thrombotic risk STEMI patients, and now we can at least think about shortening it, whether for all patients or for higher-bleeding-risk patients,” observed Dr. Stone, professor of medicine at Columbia University in New York.

As a matter of fact, DAPT durations even briefer than 6 months are under active investigation. Dr. Kedhi is co-principal investigator in the Onyx ONE clinical trial, a new prospective, 85-center, randomized, single-blind trial of a mere 1 month of DAPT in 2,000 high-bleeding-risk CAD patients undergoing PCI with the Resolute Onyx DES or the BioFreedom drug-coated stent.

The DAPT-STEMI trial was funded by Maasstad Cardiovascular Research. Dr. Kedhi reported receiving consultant fees and/or institutional grants from Medtronic, Abbott Vascular, Meril. OrbusNeich, Boston Scientific, AstraZeneca, and Pfizer.

SOURCE: Kedhi, E. no abst.


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