Can an 84-year-old male with a history of Atrial Fibrillation (A-fib) on warfarin (Coumadin) be switched to a Direct Oral Anticoagulant (DOAC)?

Switching from Warfarin to a DOAC for an 84-Year-Old Male with Atrial Fibrillation

This patient should be switched from warfarin to a direct oral anticoagulant (DOAC) given his non-valvular atrial fibrillation status post-TAVR and absence of mechanical heart valves or moderate-to-severe mitral stenosis. 1

Patient Assessment

• The patient has non-valvular atrial fibrillation (A-fib) with a high CHA₂DS₂-VASc score (age ≥75, hypertension, diabetes, and possibly heart failure given his history of severe AS) 1
• He has a TAVR (transcatheter aortic valve replacement) with Edwards Lifesciences SAPIEN valve, which is a bioprosthetic valve, not a mechanical valve 1
• He has no documented history of mechanical heart valves or moderate-to-severe mitral stenosis, which would be contraindications to DOAC therapy 1
• The patient has been on warfarin without reported bleeding issues and has stable INRs (implied by his comfort with monthly blood checks) 1

Benefits of Switching to a DOAC

• DOACs are recommended over vitamin K antagonists (VKAs) like warfarin in eligible patients with AF to prevent stroke and thromboembolism 1
• DOACs provide at least non-inferior efficacy compared to warfarin with a 50% reduction in intracranial hemorrhage risk 1
• Meta-analyses show that DOACs reduce the risk of stroke or systemic embolism (HR 0.81), all-cause mortality (HR 0.90), and intracranial bleeding (HR 0.48) compared to warfarin 1
• Switching to a DOAC would eliminate the need for regular INR monitoring, which may improve quality of life despite the patient's current acceptance of monthly testing 2, 3

DOAC Selection Considerations

• Apixaban might be a good option for this elderly patient (84 years old) due to its favorable bleeding profile, particularly in older adults 4, 5
• Dose adjustment would be necessary based on age ≥80 years (for dabigatran) or other criteria specific to each DOAC 1, 6
• For apixaban, dose reduction to 2.5 mg twice daily would be indicated if the patient meets two of three criteria: age ≥80 years, body weight ≤60 kg, or serum creatinine ≥133 mmol/L 1

Special Considerations for This Patient

• The patient's renal function should be evaluated before initiating DOAC therapy, as dose adjustments may be required based on creatinine clearance 1, 4
• The patient's history of COPD exacerbations should be considered when selecting a DOAC, though this does not contraindicate DOAC use 5
• The patient has a bioprosthetic valve (TAVR), which is compatible with DOAC therapy, unlike mechanical valves 1, 7
• His current use of diltiazem for rate control should be evaluated for potential drug interactions with the selected DOAC 1

Antibiotic Prophylaxis and Dental Procedures

• The patient will still require antibiotic prophylaxis for dental procedures due to his TAVR, regardless of which anticoagulant he takes 1
• The planned azithromycin prophylaxis for his upcoming dental procedure in December would remain appropriate even if switched to a DOAC 1

Potential Concerns and Management

• If the patient experiences bleeding on a DOAC, specific reversal agents are available (idarucizumab for dabigatran, andexanet alfa for factor Xa inhibitors) 8
• For planned procedures, DOACs can be temporarily discontinued without bridging therapy, unlike warfarin which often requires bridging with heparin 1
• The patient should be counseled about the importance of strict adherence to DOAC therapy, as poor adherence can lead to increased stroke risk 2

Common Pitfalls to Avoid

• Underdosing DOACs is not recommended unless patients meet specific criteria for dose reduction, as this can lead to inadequate stroke prevention 1
• Patients with a history of poor warfarin TTR (time in therapeutic range) may have higher risk of DOAC non-adherence, so adherence should be emphasized and monitored 2
• Abrupt discontinuation of warfarin without proper transition to a DOAC could leave the patient temporarily unprotected from thromboembolism 6

In conclusion, this 84-year-old male with non-valvular atrial fibrillation and a bioprosthetic valve (TAVR) should be switched from warfarin to a DOAC, with appropriate dose adjustment based on his age and renal function. This change would likely improve his quality of life by eliminating the need for regular INR monitoring while providing at least equivalent stroke prevention with reduced risk of intracranial hemorrhage.