Table 1.

Trial inclusion and exclusion criteria

Inclusion criteria
	1. Male or female at least 18 years of age at the time of giving informed consent.
	2. Able to receive warfarin with a target INR 2.0 to 3.0
	3. Able to take low-dose aspirin at a dose of 75–100 mg daily or have a documented contraindication to aspirin use.
	4. Implantation of an On-X mechanical valve in the aortic position at least 3 months (90 days) prior to enrollment.
	5. If female participant of childbearing potential, including those who are less than 2 years post-menopausal, she must agree to and be able to use a highly effective method of birth control (eg, barrier contraceptives [condom or diaphragm with spermicidal gel], hormonal contraceptives [implants, injectables, combination oral contraceptives, transdermal patches, or contraceptive rings], intrauterine devices, or sexual abstinence) continuously through the study until the last study visit.
	6. Able to provide written informed consent
Exclusion criteria
	1. Mechanical valve in any position other than aortic valve.
	2. Any cardiac surgery in the 3 months (90 days) prior to enrollment.
	3. Need to be on aspirin >100 mg daily or a P2Y12 inhibitor (clopidogrel, ticagrelor, prasugrel, or ticlopidine).
	4. Known hypersensitivity or other contraindication to apixaban.
	5. On dialysis or a creatinine clearance > 25 mL/min.
	6. Experienced an ischemic stroke or intracranial hemorrhage within 3 months of screening for enrollment.
	7. Active pathological bleeding at the time of screening for enrollment.
	8. Active endocarditis at the time of screening for enrollment.
	9. Pregnant at the time of screening for enrollment, plan to become pregnant at any point during the study, or are breast feeding at the time of screening for enrollment.
	10. On concomitant combined strong P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4) inducers or inhibitors.
	11. History of non-compliance with recommended monthly INR testing.