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Purpose and principlesIndications, selection and cautionsAssessment before treatmentTreatment approachRegimens, contraindications and interactionsComplications, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Anticoagulation in cardiovascular disease

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Time-critical presentation

Major bleeding, suspected intracranial haemorrhage, acute embolic stroke or thrombosed mechanical valve requires immediate emergency assessment; record the exact anticoagulant, dose and last ingestion while resuscitation proceeds.

Purpose and principles

Use oral anticoagulation safely for cardiovascular thromboembolism prevention, especially atrial fibrillation, cardioversion and mechanical valves.

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.

Indications, selection and cautions

AF needing risk assessment

Any documented paroxysmal, persistent or permanent AF or typical atrial flutter should prompt structured stroke and bleeding assessment.

Acute embolismRed flag

Sudden focal neurology, painful pulseless limb or visceral ischaemia may represent embolism despite or without treatment.

Major bleedingRed flag

Haemodynamic instability, intracranial features, ongoing GI bleeding or a substantial haemoglobin fall needs urgent reversal planning.

Mechanical valve

A mechanical prosthesis changes drug choice: DOACs are unsuitable and INR targets depend on valve type, site and risk factors.

Accumulation risk

Acute kidney injury, dehydration, low body weight, advanced age and strong P-gp/CYP3A inhibitors may increase DOAC exposure.

Assessment before treatment

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 05
    Echocardiography
    Why
    Assess valves, chamber size and ventricular function; TOE may exclude atrial thrombus before early cardioversion.

Treatment approach

01FirstAF stroke preventionFirst stepConfirmed AF or atrial flutter.+
  1. 1Confirm the rhythm and identify mechanical valves, rheumatic mitral stenosis and reversible precipitants.
  2. 2Calculate CHA2DS2-VASc and ORBIT; correct blood pressure, anaemia, renal impairment, alcohol excess and interacting medicines where possible.
  3. 3Offer a DOAC when indicated and eligible, using Cockcroft-Gault CrCl and the product-specific reduction criteria.
  4. 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.+
  1. 1Provide therapeutic anticoagulation for at least 3 weeks before cardioversion, or use a TOE-guided strategy when earlier cardioversion is appropriate.

Regimens, contraindications and interactions

First-line DOAC option for eligible AF.

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.

Once-daily DOAC option for eligible AF.

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.

Required for mechanical prosthetic valves and used where DOACs are unsuitable.

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.

Complications, monitoring and follow-up

  • 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.

Special situations

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.

Common pitfalls

  1. 01

    Using eGFR instead of Cockcroft-Gault CrCl to choose a DOAC dose.

  2. 02

    Reducing a DOAC dose without meeting its product-specific criteria.

  3. 03

    Giving a DOAC to a patient with a mechanical valve.

  4. 04

    Stopping anticoagulation because AF is not seen on one ECG.

  5. 05

    Using ORBIT or falls risk as an automatic reason not to anticoagulate.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Renal function for DOAC dosing

An 84-year-old with AF is being assessed for a DOAC. Which renal estimate should guide dose selection?

Choose one answer, then submit
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Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG196: Atrial fibrillationStroke/bleeding assessment, DOAC choice and review.
  • MHRA: DOAC bleeding risk and reversal agentsRenal dosing, bleeding precautions and reversal.
  • MHRA: renal-function estimates for medicinesCockcroft-Gault for DOAC dosing.
  • Apixaban 5 mg SmPCAF dosing and reduction criteria.
  • Rivaroxaban SmPCAF and VTE dosing.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Review renal function, adherence, interacting medicines and bleeding regularly; DOACs do not require routine INR monitoring.
Interpretation and limitations
Moderate-to-severe rheumatic mitral stenosis or a mechanical valve favours a vitamin K antagonist, not a DOAC.
2
Confirm 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.+
    1. 1Stop the anticoagulant, resuscitate, control the source and record agent, dose, last intake, renal function and concomitant antiplatelets.
    2. 2Seek immediate haematology and relevant procedural input; use specific reversal when nationally indicated and available.
    3. 3For warfarin-associated major bleeding, reverse rapidly with intravenous vitamin K and prothrombin complex concentrate under the major-haemorrhage pathway.
    4. 4Reassess thrombotic indication and document when and how anticoagulation will be restarted after haemostasis.