The major academic focus for my decision to recommend extension of dual antiplatelet therapy (DAPT) beyond one year following implantation of a second generation drug eluting stent (DES) derives from the excellent DAPT trial data.¹ The authors report, in addition to the reduced rates of stent thrombosis (1.4% with placebo and 0.4% with continued dual antiplatelet therapy, p<0.001), a reduction in the major adverse cardiovascular and cerebrovascular events (4.3% compared with 5.9% in the control population who received aspirin alone, p<0.001), and a lower rate of myocardial infarction (2.1% vs 4.1%, p<0.001). This suggests benefit of such therapy not only for the stent per se, but in the native circulation. Not unanticipated was the increased rate of moderate or severe bleeding with continued thienopyridine treatment (2.5% vs 1.6%, p=0.001).

Thus, my decision for long-term DAPT as compared with aspirin monotherapy is based less on stent issues and more on outcomes related to the cardiovascular bed in these obviously highly vulnerable patients. There are three decision-making components impacting my recommendation. The first two are essentially mechanical, the initial one related to minor or major bleeding complications and the patient’s willingness to tolerate “nuisance” bleeding that incurred during the year of DAPT; the second is dependent on the patient’s ability to afford or the insurer’s willingness to support long-term thienopyridine management. These two variables also appear as the major determinants of patient preference. Another obvious variable is the potential need for planned (or indeed deferred) invasive therapies or procedures following the year of thienopyridine use. The recent ACS in the case example cited is in accordance with the guideline identification of increased benefit with prior MI.

However, of major concern is the patient’s underlying atherosclerotic burden – what is the spectrum of cardiovascular events that has occurred prior to the DES implantation, what is known from the invasive or noninvasive studies about the atherosclerotic burden in the vasculature? These aspects are not addressed in the 2016 Guideline Focused Update on Duration of Dual Antiplatelet Therapy.² The patient’s uncontrolled or poorly-controlled risk factor spectrum is another contributory variable to the assessment of the atherosclerotic landscape.

Patients enrolled in clinical trials include those with increased ischemic risk, those with increased bleeding risk, and those with equipoise for these two factors. Clinical trial results depict the “average” of such patients and each clinician must ascertain for the individual patient (personalized medicine) where in the spectrum each patient resides. Use of more potent P2Y12 inhibitors confers decreased ischemic risk but increased bleeding risk. An important emphasis is that extended DAPT study data are limited to several years, rendering the ideal duration of such therapy unknown.

Patients on extended DAPT who develop atrial fibrillation and require oral anticoagulation are at even more accentuated bleeding risk. I favor the discontinuation of aspirin and the continuation of the P2Y12 inhibitor, pending the results of ongoing randomized clinical trials. I have inadequate experience with the DAPT score, but would recommend its inclusion in the electronic medical record to provide some objective assessment of the features guiding the individual decision made by the clinician.

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References

1. Mauri L, Kereiakes DJ, Yeh RW, et al. Twelve or 30 months of dual antiplatelet therapy after drug-eluting stents. N Engl J Med 2014;371:2155-2166.
2. Levine GN, Bates ER, Bittl JA, et al. 2016 ACC/AHA Guideline Focused Update on Duration of Dual Antiplatelet Therapy in Patients With Coronary Artery Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2016;():. doi:10.1016/j.jacc.2016.03.513.

Keywords: Aspirin, Atrial Fibrillation, Drug-Eluting Stents, Electronic Health Records, Hemorrhage, Insurance Carriers, Myocardial Infarction, Patient Preference, Risk Factors, Stents, Thienopyridines, Thrombosis

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