What is the best course of action for an older adult with a history of atrial fibrillation, currently on coumadin (warfarin), who presented with a transient neurological event, complete resolution of symptoms, and a brain MRI showing a right hippocampus FLAIR T2 abnormality, with impaired renal function and recent lumbar puncture?

Hospital Summary and Discharge Management

Clinical Summary

This patient requires continuation of therapeutic anticoagulation with warfarin for atrial fibrillation, with careful monitoring of renal function and INR, while completing outpatient workup for the right hippocampal abnormality that is most likely not infectious in nature. 1, 2

Hospital Course Overview

Admission (HD #1): Patient with atrial fibrillation on warfarin presented with transient neurological symptoms that completely resolved prior to ED arrival. CTA brain/neck unremarkable, no focal deficits identified. 1

HD #2-3: Neurologically stable in sinus rhythm. Brain MRI revealed right hippocampus FLAIR T2 abnormality with possible enhancement—atypical for HSV/VZV infection, not consistent with post-ictal changes, less likely mass per neurology. 1

HD #4-5: Warfarin held, bridged to heparin for lumbar puncture preparation. INR drifted to 1.4 (target <2.0 for interventional radiology). EEG negative for seizure activity. 1, 2

HD #6-7: Acute kidney injury developed (elevated creatinine). Nephrotoxic medications held (ARB, beta-blocker, statin, furosemide). First LP attempt unsuccessful. 3

HD #8-9: Successful LP performed. Heparin held post-procedure per surgery. Creatinine improving to 1.33. Warfarin restarted at 7.5mg with plan for low-intensity heparin (anti-Xa goal 0.2-0.3) starting 6 hours post-LP. 1, 2

Discharge Recommendations

Anticoagulation Management

Resume therapeutic warfarin immediately with target INR 2.0-3.0 for stroke prevention in atrial fibrillation. 1, 2 The patient experienced a transient neurological event (likely TIA) in the setting of atrial fibrillation, which places them at high risk for recurrent stroke. 1

• Warfarin dosing: Continue home dose schedule (5mg alternating with 7.5mg as documented) with INR target 2.5 (range 2.0-3.0). 1, 2
• Bridge therapy: Continue low-intensity heparin (anti-Xa 0.2-0.3) until INR ≥2.0 for at least 2 consecutive days, given recent LP and bleeding risk. 1
• INR monitoring: Check INR within 3-5 days post-discharge, then weekly until stable, then monthly when therapeutic range maintained. 1, 2

Critical Consideration for Renal Function

The acute kidney injury significantly impacts warfarin management and stroke risk. 3 Patients with atrial fibrillation and impaired renal function who present with ischemic events on warfarin have higher baseline creatinine and lower GFR. 4

• Monitor creatinine weekly until stable, then monthly. 3
• Avoid nephrotoxins until creatinine returns to baseline. 3
• Consider dose adjustment of warfarin if renal function continues to decline, as impaired renal function may contribute to stroke occurrence despite adequate anticoagulation. 4, 3

Neurological Follow-up

The right hippocampal FLAIR abnormality requires outpatient follow-up but does not change anticoagulation management. The negative EEG, atypical imaging for infection, and clinical stability suggest this is not an acute infectious or seizure-related process requiring immediate intervention.

• Repeat MRI brain in 6-8 weeks to assess for interval change. 1
• Neurology follow-up within 2-4 weeks with LP results and repeat imaging. 1
• No empiric antiviral therapy indicated given atypical presentation for HSV/VZV encephalitis and clinical stability. 1

Stroke Risk Stratification

This patient is at high risk for recurrent stroke based on: 1

• History of transient neurological event (TIA equivalent) in setting of atrial fibrillation
• Subtherapeutic anticoagulation at presentation (INR 1.4 documented on HD #5)
• Impaired renal function (creatinine 1.33, likely higher baseline given AKI)
• Age >65 years (implied by "older adult" designation)

The annual stroke risk without adequate anticoagulation is 5-12% based on CHADS₂-VASc scoring. 1 Approximately 44.5% of atrial fibrillation patients on warfarin have subtherapeutic INRs at hospital presentation, and these patients are significantly more likely to experience thromboembolic events. 5

Medication Reconciliation

Resume cardiac medications cautiously given recent AKI: 3

• Hold ARB, beta-blocker, and furosemide until creatinine <1.2 or returns to baseline
• Resume statin once creatinine stable (not nephrotoxic but held during AKI workup)
• Continue warfarin as primary therapy—do not substitute aspirin monotherapy, which is inadequate for stroke prevention in atrial fibrillation. 1, 6

Important Caveats

Do not use aspirin monotherapy or add aspirin to warfarin unless this patient has concurrent coronary artery disease requiring dual therapy. 6 Aspirin alone is never appropriate for stroke prevention in atrial fibrillation regardless of stroke risk. 1, 6

Do not switch to direct oral anticoagulants (DOACs) during this acute period with fluctuating renal function and recent procedural bleeding risk. 1 DOACs may be considered later if warfarin management proves difficult, but only after renal function stabilizes. 7, 3

Ensure close INR monitoring as approximately 50% of treated atrial fibrillation patients remain inadequately anticoagulated despite warfarin therapy. 5 The combination of impaired renal function and recent subtherapeutic INR places this patient at particularly high risk for recurrent events. 4, 3