New guidelines decrease the minimum duration of dual-antiplatelet therapy (DAPT) to as little as 3 months after drug-eluting stent placement in certain lower-risk patients with coronary artery disease.
The updated recommendations harmonize and replace six other guidelines, and apply to everolimus and zotarolimus stents, not Cypher or Taxus stents, said Dr. Eric R. Bates, who helped author the American College of Cardiology/American Heart Association Focused Update. “The emphasis is on balancing ischemic risk versus bleeding risk. The recommendations give clinicians guideline coverage to make personalized DAPT recommendations,” he said in an interview.
Dr. Eric Bates
The guidance reflects recent evidence that shorter duration (3-6 months) of DAPT, compared with the standard 12 months of therapy does not increase the risk of stent thrombosis and potentially lessens bleeding risk in select patients. Other studies of an additional 18 or 36 months of DAPT found a decrease in the risk of MI and stent thrombosis, at the cost of greater risk of bleeding. Thus, the updated guidelines call for “a thoughtful assessment of the benefit-risk ratio, integration of study data, and consideration of patient preference” when selecting duration of DAPT. “In general, shorter-duration DAPT can be considered for patients at lower ischemic risk with high bleeding risk, whereas longer-duration DAPT may be reasonable for patients at higher ischemic risk with lower bleeding risk,” the authors wrote, led by Dr. Glenn N. Levineof Baylor College of Medicine, Houston (J Am Coll Cardiol. 2016 Mar 29. doi: 10.1016/j.jacc.2016.03.512).
The recommendations define DAPT as combination therapy with aspirin and a P2Y12 receptor inhibitor – that is, clopidogrel, prasugrel, or ticagrelor. “When indicated, ticagrelor and prasugrel have a Class IIa preference over clopidogrel,” Dr. Bates said. The recommended daily dose of aspirin is 81 mg (range, 75-100 mg), which is usually continued indefinitely, regardless of how long patients receive dual therapy.
The shortened durations of dual-antiplatelet therapy include several scenarios. For elective percutaneous coronary intervention, the former Class I recommendation for 12 months of DAPT has been reduced to 6 months, with a Class IIb recommendation for either longer treatment or shorter (3-month) treatment, Dr. Bates, professor of medicine at the University of Michigan Health System in Ann Arbor, said. For patients with acute coronary syndrome, the guidelines retain the Class I recommendation for 12 months of DAPT, but also add a Class IIb recommendation for longer or shorter (6 months) DAPT.
The guidelines also include a new Class IIb recommendation for 12 months of DAPT started early after coronary artery bypass graft in patients with stable ischemic heart disease. This strategy “may be reasonable to improve vein graft patency” in these patients, the recommendations state.
The guidance clarifies previous recommendations on the timing of elective noncardiac surgery, and assigns Class IIb support for consideration of such surgeries starting 3 months after implantation of drug-eluting stents, if the risks of delaying surgery outweigh the expected risk of stent thrombosis when it is necessary to stop P2Y12 inhibitor therapy.
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Blood cells in the blood vessel
The recommendations now distinguish between B and C levels of evidence to increase granularity, according to Dr. Bates. The document updates recommendations on duration of DAPT across six previously published guidelines – the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention (PCI); the 2011 ACCF/AHA Guideline for Coronary Artery Bypass Graft Surgery; the 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease; the 2013ACC/AHA Guideline for the Management of ST-Elevation Myocardial Infarction; the 2014 ACC/AHA Guideline for Non-ST-Elevation Acute Coronary Syndromes, and the 2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery.
The extensive evidence review that informed guideline development was simultaneously reported by Dr. John Bittl at Munroe Regional Medical Center in Ocala, Fla., and his colleagues. The investigators synthesized evidence from 11 randomized controlled trials of more than 33,000 patients who received mainly newer generation stents. They also reviewed a randomized controlled trial of more than 21,000 patients with stable ischemic heart disease who were more than 1 year post-MI, and a post hoc analysis of a trial of more than 15,000 such patients.
These reviews uncovered “moderately strong evidence” that prolonged DAPT after implantation of newer generation drug-eluting stents “entails a trade-off between reductions in stent thrombosis and MI and increases in major hemorrhage,” Dr. Bittl and his colleagues wrote. Likewise, they found moderately strong evidence that prolonged DAPT helps prevent cardiovascular events at the cost of increased bleeding in patients whose coronary thrombotic risk stemmed from prior MI, not stent implantation. They found weak evidence of increased mortality in stent patients who received prolonged DAPT.