Atrial fibrillation patients with risk factors for stroke and systemic embolism require long-term anticoagulant therapy. Recently, non-vitamin K antagonist oral anticoagulant (NOAC) has shown their excellent safety and efficacy, and thus are widely accepted in clinical practice. Meanwhile, after percutaneous coronary intervention (PCI) using the drug-eluting stents due to coronary artery disease, the administration of one or more antiplatelets is essential to prevent the recurrence of stent thrombosis and myocardial infarction. Combined administration of anticoagulants and antiplatelets significantly lowers the incidence of ischemic events such as stroke and myocardial infarction, however, it also significantly increases the likelihood of bleeding leading to hospitalization, and or even death, thereby significantly affecting the clinical course of the AF patients who underwent PCI. Nevertheless, due to the very high mortality rate of stent thrombosis, the current standard of care guidelines recommend triple therapy with anticoagulants and double antiplatelet therapy (DAPT) in patients with atrial fibrillation for 1 month after coronary intervention, followed by co-administration of NOAC with single antiplatelet agent for 1 year. However, little is known after the optimal therapeutic strategy after 1 year. The purpose of this study is to compare the clinical results of single anticoagulant and clopidogrel combination therapy for maintenance therapy after 1 year in patients with atrial fibrillation.

AF patients who had undergone PCI with DES implantation at least 12 months ago will be enrolled in this study. Decision for the antiplatelet agent discontinuation would be determined by randomization. Apixaban or Rivaroxaban would be prescribed to reduce the risk stroke or systemic embolism evoked by AF, and the administration of Warfarin, a vitamin-K dependent anticoagulant, would also be allowed according to attending physician's decision. The following criteria should be followed for the reduction of dosages according to the patient's renal function and other systemic conditions. Warfarin is administered to patients with creatinine clearance < 15 ml/min or dialysis. The drugs used in this study correspond to the international treatment guidelines after coronary intervention in patients with atrial fibrillation.NOAC and antiplatelet agents would be prescribed upon an outpatient visit. Clinical outcome would be followed for 2 years after study enrollment and randomization.

Screening

• Baseline Serum AST/ALT level

• Creatinine clearance (mL/min)

• Concurrent administration of CYP3A4 agents: Ketoconazole, Itraconazole, Iopinavir/ritonavir, indinavir/ritonavir, conviaptan

  # Dose Adjustment Criteria for Apixaban

  @ Meeting 2 of 3 following criteria

• Serum creatinine level > 1.5 mg/dL

• Body weight under 60 kg

• age over 80 years old

  # Dose Adjustment Criteria for Rivaroxaban

• eGFR from 15-49 mg/min

Inclusion Criteria:

1. over 19 years old
2. Patient who underwent PCI with DES more than 12 months ago
3. Non-valvular atrial fibrillation patients requiring long-term anticoagulation

Exclusion Criteria:

1. Over 85 years old
2. Pregnancy or Potential Pregnancy
3. Life expectancy within 1 year
4. Patients who refuse or do not understand the written consent form
5. Requiring anticoagulation due to history of mechanical valve replacement, mitral stenosis or deep vein thrombosis
6. Coagulopathy, continuous bleeding, or Hb level below 10 g/dL
7. Intracerebral hemorrhage within 2 months
8. Patients with gastrointestinal hemorrhage within three months of registration
9. Patients diagnosed with a gastrointestinal tumor that requires continuous treatment
10. Patients treated with 1st generation drug-eluting stents (Cypher, Taxus, or Endeavor Sprint)