How does anticoagulation differ between nonvalvular atrial fibrillation and valvular atrial fibrillation?

• A. Nonvalvular AF is treated with DOACs or warfarin; valvular AF (with mechanical valves or rheumatic MR/AS) requires warfarin
• B. Nonvalvular AF requires warfarin only; valvular AF can use DOACs
• C. Nonvalvular AF uses aspirin; valvular AF uses warfarin only
• D. Both can be managed with DOACs

Answer: (A)

Anticoagulation choices hinge on whether atrial fibrillation is associated with a mechanical valve or rheumatic valve disease. In nonvalvular AF, DOACs are approved and commonly preferred because they provide similar protection against stroke as warfarin but with fixed dosing and less monitoring. In contrast, valvular AF that involves a mechanical heart valve or rheumatic mitral stenosis is not treated with DOACs; evidence shows warfarin remains necessary to prevent thromboembolism in these situations. Trials and guidelines have shown increased risk with DOACs in mechanical valves (and DOACs have not proven safe/effective in rheumatic mitral stenosis), so warfarin is the recommended anticoagulant for those patients. Thus, the statement that nonvalvular AF can be treated with either a DOAC or warfarin, while valvular AF with mechanical valves or rheumatic MR/AS requires warfarin, best captures the distinction.