Point/Counterpoint: Dual antiplatelet therapy for vascular patients: Yes, no, or sometimes?
Dueling over dual antiplatelet therapy
Joseph L. Mills Sr., M.D.
Amidst a background of constant clamoring for data-driven and evidence-based medical decision-making, the practice of vascular medicine and surgery remains mired in the anecdotal. If a little is good, more must be better, seems the rationale for dual antiplatelet therapy. There may be small, as yet unclearly defined subsets of patients for whom dual therapy is actually beneficial, but an unbiased review of the current literature leads to the inescapable conclusion that more patients would be harmed by injudicious application of the more-is-better principle as concerns antiplatelet therapy for patients with carotid artery and peripheral artery disease (PAD).
The best evidence for antiplatelet therapy in patients with carotid disease suggests that aspirin as a single agent in doses ranging from 75 to 150 mg daily is preferred, and at least two meta-analyses and systematic reviews were unable to support the use of dual antiplatelet therapy.1 At least in symptomatic patients, combination or dual antiplatelet therapy may increase the short-term risk of hemorrhagic complications in patients with acute ischemic stroke caused by large-artery disease.2 Long-term dual therapy for secondary stroke prevention with aspirin and clopidogrel has been associated with four times the bleeding risk of monotherapy.3 These bleeds are often intracranial or gastrointestinal and are serious.
With respect to asymptomatic patients, while the CHARISMA trial did demonstrate a modest reduction in subsequent thrombotic events in a subset analysis of patients with stable, preexisting vascular disease, the bottom line was that dual antiplatelet therapy was associated with a 4% risk of moderate to severe bleeding and that there were strong correlations between moderate bleeding and all cause mortality (hazard ratio, 2.55), myocardial infarction (HR, 2.92) and stroke (HR, 4.2).4 The bleeding risk of dual antiplatelet therapy thus seems to outweigh the benefits.
Other data muddy the situation, but only a little. While at least two small studies (one a randomized controlled trial – CARESS [Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic Carotid Stenosis])5 have suggested that the combination of aspirin and clopidogrel may reduce the frequency of perioperative microembolic signals detected early after carotid endarterectomy compared with monotherapy, it is not established that this surrogate measure would translate into long-term clinical benefit and would outweigh the established bleeding risk of dual therapy.
At present, the vascular surgeon should urge his patients to stop smoking, prescribe a statin, control blood pressure (but not necessarily with a beta-blocker), control diabetes, and prescribe a single antiplatelet agent, most often baby aspirin, for most of his or her patients. More good than harm will result.
References
Dr. Mills is professor of surgery and chief, division of vascular and endovascular surgery, University of Arizona Health Sciences Center, Tucson, and an associate medical editor for Vascular Specialist. He has no relevant conflicts.
