Intervention: Warfarin
Trial phase: Phase 2 | Phase 3
ATC code: B01AA03
SMILES: CC(=O)CC(c1ccccc1)c1c(O)c2ccccc2oc1=O
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 28
Group description: While patients are hospitalized, warfarin will be dosed daily, with daily INR monitoring per hospital protocol. Daily doses may vary from 0.5mg to 15mg by mouth, as determined by patient specific factors such as patient size, hepatic function, INR, concomitant medications, diet, or other factors. Based on these factors or others not listed, there may also be days in which the patient is prescribed to not get does not receive a dose of warfarin.

After discharge from the hospital, warfarin dosing will be subsequently managed by an anticoagulation clinic, per established protocols. All patients will have a goal INR of 2-3 during the duration of the study. The duration of therapy will be at least 30 days. The patient's physician may determine that anticoagulation therapy should be continued after the study period, based on their examination of the patient at the 30-day post-operative examination.

Warfarin: Study arm that patient can be randomized to. Warfarin therapy has been the mainstay of therapy for patients with POAF. While the duration of therapy is usually short (3-4 weeks), complications of anticoagulation do occur. Additionally, warfarin therapy for POAF is associated with increased length of stay, need for monitoring, and bleeding complications.
Eligibility criteria:
Inclusion Criteria:

Signed Written Informed Consent
Patients diagnosed with new-onset persistent or recurrent atrial fibrillation after isolated CABG surgery. Persistent atrial fibrillation is defined as an episode of >12 hours. Recurrent atrial fibrillation is defined as two or more episodes of atrial fibrillation lasting longer than 30 minutes.
Women of childbearing potential (WOCBP) must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of study drug. Patients undergoing isolated CABG must have this tested and documented prior to the procedure, and this will be verified prior to randomization.
Women must not be breastfeeding.
WOCBP must agree to follow instructions for method(s) of contraception for the duration of treatment with study drug(s): 30 days of treatment plus 5 half-lives of study drug Apixaban (3 days) or warfarin (8 days) plus 30 days (duration of ovulatory cycle) for a total of 38 days post-treatment completion.
Males who are sexually active with WOCBP must agree to follow instructions for method(s) of contraception for the duration of treatment with study drug(s): 30 days of treatment plus 5 half-lives of study drug Apixaban (3 days) or warfarin (8 days) plus 90 days (duration of sperm turnover) for a total of 98 days post-treatment completion.

Exclusion Criteria:

Atrial fibrillation due to a reversible cause other than recent surgery
Patients diagnosed with persistent or paroxysmal atrial fibrillation chronically before undergoing surgery
Patients with mechanical heart valves
Patients currently experiencing active bleeding precluding initialization of anticoagulation therapy in the opinion of their managing physician, or with increased bleeding risk (as determined by the attending surgeon) believed to be a contraindication to anticoagulation at the time of randomization Planned major surgery requiring stoppage of anticoagulation therapy during trial period
Stroke within the previous 7 days
Moderate or severe mitral stenosis
Conditions other than atrial fibrillation that required anticoagulation (prosthetic mechanical heart valve)
Patients taking warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, clopidogrel, ticagrelor, or enoxaparin at home for any indication in the 15 days prior to surgery
Patients requiring the use of clopidogrel or ticagrelor during the study period
Severe renal insufficiency (serum creatinine level of >2.5 mg/dL or CrCL<25 ml/min) for consecutive measurements
Allergies to warfarin or apixaban, or components of warfarin or apixaban