Long-term Anticoagulation With Oral Factor Xa Inhibitor Versus Vitamin K Antagonist After Mechanical Aortic Valve Replacement

People who receive a mechanical heart valve replacement need to take blood thinners for the rest of their lives to prevent dangerous blood clots forming on the artificial valve. The standard medication for this has long been vitamin K antagonists (like warfarin), but these drugs require regular blood test monitoring and have many food and drug interactions. Newer blood thinners called factor Xa inhibitors (like rivaroxaban) are easier to use but have not been well-studied in patients with mechanical heart valves. This trial tests whether a factor Xa inhibitor is a safe and effective alternative to vitamin K antagonists for patients with a modern mechanical aortic valve. Participants must be at least 3 months past their aortic valve replacement surgery and have a well-functioning prosthetic valve. The trial excludes patients with many conditions that would make it unsafe to switch blood thinner types, including those with certain other heart conditions, bleeding disorders, or kidney/liver problems. You may be eligible if: - You are 19 years of age or older - You had mechanical aortic valve replacement at least 3 months ago - Your valve is a modern-generation mechanical valve functioning properly - Your heart function is good (NYHA class I or II) - You do not have significant other heart valve problems You may NOT be eligible if: - You have had a hemorrhagic (bleeding) stroke - You have severe kidney failure (creatinine clearance below 15 mL/min) or are on dialysis - You have poor heart function (ejection fraction 40% or less) - You have significant liver disease - You have a history of recent serious bleeding - You are pregnant or trying to become pregnant - You have a mechanical valve in any other heart valve position (mitral, tricuspid, or pulmonary) - You are under 19 years of age Talk to your doctor to see if this trial is right for you.