Invited Lecture II
From Evidence to Practice
The “Optimal” Duration of Dual Antiplatelet Therapy Following DES Revascularization
——Live Interview with Professor David E. Kandzari
<International Circulation>: How do you determine the “optimal” duration of dual antiplatelet therapy following DES revascularization？How many factors should be involved in consideration of the duration of dual antiplatelet therapy following DES revascularization？
Dr. Kandzari: Our current recommendations in the United States and some European countries are for patients who receive a drug-eluting stent to receive aspirin indefinitely combined with at least one year of thenopyridine therapy. We must understand that the primary motivator for this is a concern for stent thrombosis， and the use of drug-eluting stents for some clinicians has been assumed to require lifelong antiplatelet therapy while other clinicians do not believe that even one year of thenopyridine treatment is required. Therefore， we have a great deal of variability in clinical practice and a great deal of uncertainty. This issue of what the optimal duration of dual antiplatelet therapy is after DES revascularization challenges every clinician who is involved in the care of a patient who is being considered for a drug-eluting stent or even patients who have already received drug-eluting stents. The only way that we can truly define the best duration of antiplatelet therapy is through the performance of clinical trials that will not only evaluate safety outcomes like bleeding but also balance that with efficacy outcomes in terms of reducing death， myocardial infarction， and stent thrombosis. Even then the story becomes very challenging when we consider that there might be differences in the risk of stent thrombosis between different types of DES and more recently there is emerging evidence suggesting that there may differences among individuals in their responses to antiplatelet therapy. To date， our recommendations for one year of antiplatelet therapy are derived largely from observation studies that have suggested that longer term durations may reduce the risk of death and M.I. but not necessarily stent thrombosis. The second motivator for our current guideline recommendations is this intuitive perception that longer term durations of dual antiplatelet therapy could reduce late stent thrombotic complications. Ultimately， we must realize that most of the current recommendations are based on more on opinion rather than clinical trial evidence. In fact， most of the observational data that we have today indicates that beyond six months， treatment with dual antiplatelet therapy may not reduce the risk of stent thrombosis and in a broad all-comers population it may not even reduce the risk of death and myocardial infarction. Just recently， one randomized trial further suggests that major adverse events， including stent thrombosis and bleeding， may not significantly differ between 12 and 24 months of dual antiplatelet therapy following DES revascularization.
<International Circulation>: Does the duration of dual antiplatelet therapy of post-DES procedures differ from that of post-BMS procedures？
Dr. Kandzari: Historically， the standard duration of thenopyridine treatment after a BMS has been 2~4 weeks and that is very different from our current recommendations after drug-eluting stent placement. And yet， most of the studies suggesting benefit of longer duration in patients with acute coronary syndromes included those treated with bare metal stents. Probably the most common reason bare-metal stents are used today is because there is a perception that patients may not be able to take longer dual antiplatelet therapy. What we do not know is whether long term dual antiplatelet therapy after a BMS confers the same benefit as after a DES and so some forthcoming trials will address this issue by including both bare-metal and drug-eluting stent treated patients.
<International Circulation>: How do new stent designs such as bioabsorbable stents affect dual antiplatelet therapy duration?
Dr. Kandzari: I think that is a concept that is promising but still needs to be proven specifically to whether or not stents with a bioabsorbable polymer that can conceptually go back to a bare-metal stent can reduce the risks late term of stent thrombosis or improve safety. Intuitively， it seems to be the case， but conceptually it is one that needs to be proven over long term follow-up. I think that whether it is with bioabsorbable polymers or bioabsorbable stents， whether we can abbreviate antiplatelet therapy is something that needs to be studied.
<International Circulation>: How do you plan for antiplatelet therapy after DES revascularization for left main coronary artery disease? Are there any special considerations compared to intervention for other coronary lesions?
Dr. Kandzari: In the left main indication， stent thrombosis can be clinically catastrophic and so for many clinicians this would be an instance in which they might recommend lifelong dual antiplatelet therapy. It turns out， however， that the risks of stent thrombosis in the left main setting are relatively uncommon. They may be even less common than in other lesion complexities. It may be related to the large caliber of left main artery being associated with a lower incidence of stent thrombosis. Many clinicians would prescribe longer durations in the left main setting but whether it is necessary or not is something we will learn more about in the upcoming EXCEL trial. The EXCEL trial is going to be sponsored by Abbot Vascular and it will enroll about 2500 patients globally and will randomize patients to either surgery or PCI for unprotected left main disease. The recommendations in that trial will be at least one year according to current guidelines but certainly many clinicians by preference will treat patients for longer durations and we will learn more about the risks and benefits of shorter and longer durations from that trial.
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