01Purpose and principlesWhat the treatment does and how it fits into care.
Anticoagulants inhibit the coagulation cascade and prevent fibrin-rich thromboembolism. The indication, renal function, valve status, adherence and bleeding risk determine the agent and dose.
Stroke and bleeding risks change over time. Shared decision-making includes the expected benefit, bleeding precautions, reversibility, peri-procedural plan and the consequences of missed doses.
Key points
- Use CHA2DS2-VASc to assess AF-related stroke risk and ORBIT to identify modifiable bleeding risk; a bleeding score is not an automatic reason to withhold treatment.
- Offer a DOAC first line for eligible non-valvular AF when anticoagulation is indicated.
- Do not use a DOAC for a mechanical prosthetic valve; use a vitamin K antagonist with the valve-specific INR target.
- Do not substitute aspirin for anticoagulation in AF stroke prevention.
- Do not withhold anticoagulation solely because of age or falls risk.
- Dose DOACs using Cockcroft-Gault creatinine clearance, not laboratory eGFR alone.
- Review renal function, adherence, interacting medicines and bleeding regularly; DOACs do not require routine INR monitoring.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Any documented paroxysmal, persistent or permanent AF or typical atrial flutter should prompt structured stroke and bleeding assessment.
Sudden focal neurology, painful pulseless limb or visceral ischaemia may represent embolism despite or without treatment.
Haemodynamic instability, intracranial features, ongoing GI bleeding or a substantial haemoglobin fall needs urgent reversal planning.
A mechanical prosthesis changes drug choice: DOACs are unsuitable and INR targets depend on valve type, site and risk factors.
Acute kidney injury, dehydration, low body weight, advanced age and strong P-gp/CYP3A inhibitors may increase DOAC exposure.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
12-lead ECG or ambulatory ECGFirst step - Why
- Document AF/flutter and define rhythm burden when intermittent.
- Interpretation and limitations
- Do not diagnose AF solely from an irregular pulse or unverified consumer-device alert.
- 02
CHA2DS2-VASc and ORBIT - Why
- Structure stroke and bleeding assessment in AF.
- Interpretation and limitations
- Offer anticoagulation at CHA2DS2-VASc 2 or more; consider it for men with 1. Correct modifiable ORBIT factors rather than using the score as a veto.
- 03
FBC, renal and liver function - Why
- Find anaemia, thrombocytopenia, organ dysfunction and dose constraints.
- Interpretation and limitations
- Calculate Cockcroft-Gault CrCl for DOAC dosing and repeat after intercurrent illness.
- 04
Coagulation screen - Why
- Provide context during bleeding and monitor warfarin with INR.
- Interpretation and limitations
- A normal PT or APTT does not reliably exclude clinically relevant DOAC effect.
- 05
Echocardiography - Why
- Assess valves, chamber size and ventricular function; TOE may exclude atrial thrombus before early cardioversion.
- Interpretation and limitations
- Moderate-to-severe rheumatic mitral stenosis or a mechanical valve favours a vitamin K antagonist, not a DOAC.
04Treatment approachPreparation, options, escalation and aftercare.
01FirstAF stroke preventionFirst stepConfirmed AF or atrial flutter.+
- 1Confirm the rhythm and identify mechanical valves, rheumatic mitral stenosis and reversible precipitants.
- 2Calculate CHA2DS2-VASc and ORBIT; correct blood pressure, anaemia, renal impairment, alcohol excess and interacting medicines where possible.
- 3Offer a DOAC when indicated and eligible, using Cockcroft-Gault CrCl and the product-specific reduction criteria.
- 4If a vitamin K antagonist is required, state the target INR and establish anticoagulation-clinic follow-up.
02NextCardioversionRhythm-control cardioversion is planned and AF duration exceeds 48 hours or is uncertain.+
- 1Provide therapeutic anticoagulation for at least 3 weeks before cardioversion, or use a TOE-guided strategy when earlier cardioversion is appropriate.
- 2Confirm adherence carefully; missed DOAC doses may invalidate protection.
- 3Continue anticoagulation for at least 4 weeks after cardioversion.
- 4Base long-term continuation on stroke risk, not on apparent restoration of sinus rhythm alone.
03EscalationMajor bleeding on anticoagulationEscalationLife-threatening, uncontrolled or critical-site haemorrhage.+
- 1Stop the anticoagulant, resuscitate, control the source and record agent, dose, last intake, renal function and concomitant antiplatelets.
- 2Seek immediate haematology and relevant procedural input; use specific reversal when nationally indicated and available.
- 3For warfarin-associated major bleeding, reverse rapidly with intravenous vitamin K and prothrombin complex concentrate under the major-haemorrhage pathway.
- 4Reassess thrombotic indication and document when and how anticoagulation will be restarted after haemostasis.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Apixaban
Non-valvular AF: 5 mg orally twice daily; reduce to 2.5 mg twice daily when at least 2 apply: age 80 years or older, weight 60 kg or less, serum creatinine 133 micromol/L or more. Use 2.5 mg twice daily for CrCl 15 to 29 mL/min in AF.Active bleeding, severe hepatic disease, strong dual CYP3A4/P-gp interactions and renal impairment; not for mechanical valves.
Rivaroxaban
Non-valvular AF: 20 mg orally once daily with food; 15 mg once daily with food when CrCl is 15 to 49 mL/min.Use Cockcroft-Gault CrCl; avoid at CrCl below 15 mL/min and in mechanical valves. Strong CYP3A4/P-gp interactions and missed doses are important.
Warfarin
Individualised once-daily dosing to INR; target INR is commonly 2.0 to 3.0 for AF, while mechanical-valve targets are prosthesis- and risk-specific.Many food and medicine interactions, teratogenicity, narrow therapeutic range and major bleeding; requires reliable INR monitoring.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- At baseline and review, check FBC, liver function and Cockcroft-Gault creatinine clearance.
- Review at least annually, and more often with older age, renal impairment, frailty, intercurrent illness or interacting medicines.
- Ask specifically about missed doses, bleeding, falls circumstances, NSAIDs, antiplatelets and alcohol.
- For warfarin, monitor INR and time in therapeutic range; investigate poor control and interactions.
- Reassess CHA2DS2-VASc and the continuing indication after new comorbidity, cardioversion or apparently resolved AF.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Falls are not a veto
NICE says not to withhold anticoagulation solely because of age or falls risk; address reversible fall and bleeding hazards.
CrCl, not eGFR
Cockcroft-Gault was used in pivotal DOAC dosing and avoids dangerous overestimation in some older or low-weight adults.
Sinus rhythm does not erase risk
After cardioversion or ablation, long-term anticoagulation is driven by thromboembolic risk rather than a single rhythm check.
DOAC tests are qualitative at best
Routine PT/APTT cannot reliably quantify apixaban or rivaroxaban effect.
Combination therapy needs an end date
When PCI creates a temporary need for anticoagulant plus antiplatelet treatment, minimise duration according to the national ACS plan and bleeding risk.
08Common pitfallsFrequent interpretation and management errors.
- 01
Using eGFR instead of Cockcroft-Gault CrCl to choose a DOAC dose.
- 02
Reducing a DOAC dose without meeting its product-specific criteria.
- 03
Giving a DOAC to a patient with a mechanical valve.
- 04
Stopping anticoagulation because AF is not seen on one ECG.
- 05
Using ORBIT or falls risk as an automatic reason not to anticoagulate.