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Anticoagulation-treated patients with atrial fibrillation (AF) often receive stents, prompting the need for dual antiplatelet therapy (DAPT). To assess how best to prevent bleeding in these patients, researchers conducted a multinational, manufacturer-funded trial (PIONEER-AF) in which they randomized 2124 patients with nonvalvular AF to one of three strategies after stent placement:
Low-dose rivaroxaban (15 mg/day) plus a single P2Y12 inhibitor for 12 months
Very-low-dose rivaroxaban (2.5 mg twice daily) plus low-dose aspirin and a P2Y12 inhibitor for an investigator-chosen period of 1, 6, or 12 months
Adjusted-dose warfarin plus low-dose aspirin and a P2Y12 inhibitor for an investigator-chosen period of 1, 6, or 12 months
Clinically significant bleeding was significantly less common in the 15-mg rivaroxaban group (16.8%) and the 2.5-mg rivaroxaban group (18.0%) than in the warfarin + DAPT group (26.7%). Incidence of the composite efficacy endpoint — cardiovascular death, myocardial infarction, or stroke at 1 year — was similar among the three groups: 6.5%, 5.6%, and 6.0%, respectively.
Gibson CM et al. Prevention of bleeding in patients with atrial fibrillation undergoing PCI. N Engl J Med 2016 Nov 14; [e-pub]. (http://dx.doi.org/10.1056/NEJMoa1611594)
Comment
Although rivaroxaban (at a low or very low dose) plus antiplatelet therapy was as effective as — and safer than — warfarin plus DAPT after stenting, the trial's short-term follow-up and relatively small size limit the strength of its efficacy findings. In contrast, key previous trials of direct anticoagulants have each followed roughly 20,000 patients for several years. PIONEER-AF is more reassuring with regard to stent thrombosis, which generally occurs in the first year after stenting, than embolic events. I also find it unfortunate that this trial did not use standard-dose (20-mg) rivaroxaban given that that dose has been proven equivalent to warfarin for preventing embolic events. In effect, this trial provides clarity for interventional cardiologists but confusion for electrophysiologists. I am now comfortable with rivaroxaban plus a P2Y12 inhibitor for treating patients with recent stents and AF but am uncomfortable with the dose of rivaroxaban used in this trial.