A 62-year-old man with newly diagnosed atrial fibrillation (CHA₂DS₂-VASc score = 4) presents to the emergency department. He is haemodynamically stable with no acute symptoms. His renal function is normal (eGFR 78 mL/min/1.73m²), and he has no prior bleeding history. He is not on any anticoagulant currently. What is the most appropriate immediate next step in management?

Explanation

## Clinical Context This patient has newly diagnosed atrial fibrillation with a high stroke risk (CHA₂DS₂-VASc = 4, indicating anticoagulation is mandatory). He is haemodynamically stable with normal renal function and no contraindications to anticoagulation. ## Why DOAC Is the Next Step **Key Point:** In haemodynamically stable patients with newly diagnosed AF and no acute complications, direct oral anticoagulants (DOACs) are now preferred over warfarin and heparin for long-term stroke prevention, per current guidelines [cite:Harrison 21e Ch 276]. **High-Yield:** DOACs (apixaban, dabigatran, edoxaban, rivaroxaban) offer: - Rapid onset of anticoagulation (therapeutic levels within 2–4 hours) - No need for bridging with parenteral anticoagulants in stable AF - Predictable pharmacokinetics; no INR monitoring required - Superior or non-inferior efficacy and safety compared to warfarin in AF stroke prevention trials (ARISTOTLE, RE-LY, ROCKET-AF) **Clinical Pearl:** Apixaban 5 mg twice daily is chosen here because it has the most favourable bleeding profile in AF and is not renally dependent (unlike dabigatran and edoxaban), making it suitable for this patient with normal renal function. ## When Parenteral Anticoagulation Is Needed UFH or LMWH bridging is reserved for: - Acute coronary syndrome concurrent with AF - Haemodynamic instability or cardiogenic shock - Need for urgent cardioversion or catheter ablation within 24 hours - Severe renal impairment (eGFR < 15 mL/min) where DOACs are contraindicated This patient has none of these indications. ## Warfarin Considerations **Warning:** Warfarin is no longer first-line for AF stroke prevention in most patients. It requires: - INR monitoring (therapeutic range 2–3) - Slow onset (3–5 days to full effect); bridging with heparin is mandatory - Multiple drug and dietary interactions - Higher bleeding risk in elderly patients Warfarin is reserved for: - Mechanical heart valves (DOACs contraindicated) - Severe renal impairment (eGFR < 15) - Patient preference or inability to afford DOACs **Mnemonic:** DOAC advantages = **RAPID**: Rapid onset, Anticoagulation predictable, Parenteral bridging not needed, INR monitoring not needed, Direct (oral) administration.