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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.

Antiplatelet therapy in cardiovascular disease

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

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Time-critical presentation

Suspected stent thrombosis or ACS needs emergency assessment; major or intracranial bleeding on antiplatelets requires immediate resuscitation, haemostasis and senior cardiology/haematology input.

Purpose and principles

Select and monitor antiplatelet treatment for UK cardiovascular indications while recognising bleeding and thrombotic emergencies.

Aspirin irreversibly inhibits platelet cyclo-oxygenase; clopidogrel and prasugrel irreversibly inhibit P2Y12, while ticagrelor is reversible. Choice follows the vascular syndrome and revascularisation strategy.

Every prescription needs a documented indication, intended duration, bleeding review and plan for procedures. Combining an anticoagulant with one or two antiplatelets sharply increases bleeding risk.

Key points

  • Antiplatelets prevent platelet-rich arterial thrombosis; they are not interchangeable with anticoagulants.
  • Give aspirin as soon as possible in suspected ACS unless there is a true contraindication.
  • Dual antiplatelet therapy means aspirin plus one P2Y12 inhibitor; indication and duration depend on ACS, PCI and bleeding risk.
  • After MI, low-dose aspirin is generally continued indefinitely; clopidogrel is an alternative when aspirin is contraindicated.
  • Do not routinely prescribe aspirin for primary prevention of CVD.
  • Prasugrel is contraindicated after previous stroke or TIA and is generally unsuitable from age 75 unless a specialist judges benefit to exceed risk.
  • Never stop DAPT soon after coronary stenting without urgent advice from the treating interventional cardiology team unless life-threatening bleeding makes immediate action unavoidable.

Indications, selection and cautions

ACS or stent thrombosisRed flag

New ischaemic chest pain, dynamic ECG change, troponin rise or abrupt symptoms after PCI require emergency ACS care.

Major bleedingRed flag

Haemodynamic compromise, melaena, haematemesis, intracranial symptoms or a large haemoglobin fall are high-risk features.

Minor nuisance bleeding

Bruising or brief epistaxis is common but still warrants adherence and interaction review rather than automatic cessation.

True aspirin hypersensitivity

Clarify bronchospasm, urticaria or anaphylaxis versus dyspepsia, because the alternative strategy differs.

High gastrointestinal risk

Previous ulcer or GI bleed, older age, NSAIDs, corticosteroids, anticoagulation and heavy alcohol use increase harm.

Assessment before treatment

  1. 01
    12-lead ECG and serial troponinFirst step
    Why
    Assess suspected ACS or stent thrombosis.
    Interpretation and limitations
    Do not wait for troponin before activating emergency STEMI care when diagnostic ST elevation is present.
  2. 02
    Full blood count
    Why
    Detect anaemia or thrombocytopenia before treatment and during suspected bleeding.
    Interpretation and limitations
    Compare with baseline and assess the clinical rate and site of blood loss.
  3. 03
    Renal and liver function
    Why
    Estimate bleeding risk, procedural fitness and medicine suitability.
    Interpretation and limitations
    Organ dysfunction increases haemorrhagic risk and may change the wider antithrombotic plan.
  4. 04
    Medication and procedure reconciliation
    Why
    Confirm indication, stent date/type, intended DAPT duration and interacting drugs.
    Interpretation and limitations
    NSAIDs, anticoagulants, SSRIs and corticosteroids may materially increase bleeding risk.
  5. 05
    Bleeding-site investigation

Treatment approach

01FirstSuspected acute coronary syndromeFirst stepIschaemic chest pain or equivalent with possible ACS.+
  1. 1Perform immediate ABC assessment, 12-lead ECG and activate the national ACS/reperfusion pathway when indicated.
  2. 2Give aspirin 300 mg orally as soon as possible unless genuinely contraindicated.
  3. 3Select the P2Y12 inhibitor with the ACS and PCI strategy, age, stroke history, anticoagulation and bleeding risk in mind.
  4. 4Document the loading dose, maintenance regimen and planned duration before discharge.
02NextLong-term secondary preventionStable after MI, PCI, ischaemic stroke/TIA or symptomatic peripheral arterial disease.+
  1. 1Confirm the qualifying vascular diagnosis and whether DAPT remains required.

Regimens, contraindications and interactions

Foundation antiplatelet for ACS and established atherosclerotic disease when indicated.

Aspirin

ACS loading: 300 mg orally once; long-term secondary prevention: 75 mg orally once daily.

Active bleeding, true hypersensitivity and previous ulcer; assess GI protection. Enteric coating does not remove systemic bleeding risk.

P2Y12 inhibitor for DAPT and an alternative single agent in several secondary-prevention settings.

Clopidogrel

75 mg orally once daily. In non-ST-elevation ACS, use a 300 mg or 600 mg loading dose; a 600 mg load may be considered before PCI in adults under 75. STEMI and fibrinolysis regimens are timing- and age-specific.

Bleeding; CYP2C19 interactions. Avoid routine co-prescribing with omeprazole or esomeprazole when another suitable PPI is available. In STEMI, patients older than 75 treated medically with fibrinolysis start 75 mg without a load; a 600 mg PCI load at age 75 or older needs individual bleeding-risk assessment.

Potent P2Y12 inhibition in ACS according to the invasive strategy and bleeding risk.

Ticagrelor

180 mg orally once as a loading dose, then 90 mg twice daily for up to 12 months after ACS unless stopped earlier for a clinical reason; use with aspirin 75 to 150 mg daily.

Bleeding, dyspnoea, bradyarrhythmia, severe hepatic impairment and important CYP3A interactions.

P2Y12 inhibitor for ACS treated with PCI.

Prasugrel

60 mg orally once as a loading dose at PCI, then 10 mg once daily; use 5 mg once daily if body weight is below 60 kg and, only if chosen after specialist risk assessment, from age 75.

Complications, monitoring and follow-up

  • At every review, confirm indication, PCI date, intended stop date and who owns the plan.
  • Ask about melaena, haematemesis, haematuria, persistent epistaxis, bruising and neurological symptoms.
  • Check FBC and renal/liver function when clinically indicated, especially after bleeding or with combined antithrombotic therapy.
  • Review NSAIDs, anticoagulants, SSRIs, corticosteroids, alcohol and gastroprotection.
  • After ACS, monitor adherence closely because premature discontinuation can precipitate stent thrombosis.

Special situations

Arterial versus atrial clot

Antiplatelets reduce atherothrombosis but are not a substitute for anticoagulation to prevent AF-related embolic stroke.

DAPT has an end date

The second agent is usually time-limited; the discharge plan must state duration and exceptions.

Prasugrel history matters

A remote TIA still makes prasugrel contraindicated.

PPI selection matters

Omeprazole and esomeprazole can reduce clopidogrel activation; choose an appropriate alternative when gastroprotection is needed.

Primary prevention is not secondary prevention

The net balance supporting aspirin after MI does not justify routine aspirin before a first CVD event.

Common pitfalls

  1. 01

    Using aspirin instead of an anticoagulant for AF stroke prevention.

  2. 02

    Stopping DAPT after a recent stent without establishing the PCI indication and date.

  3. 03

    Prescribing prasugrel to someone with previous stroke or TIA.

  4. 04

    Continuing dual or triple antithrombotic therapy with no documented review date.

  5. 05

    Calling dyspepsia an aspirin allergy without clarifying the reaction.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Aspirin before a first event

A 67-year-old with hypertension and hyperlipidaemia has no history of CVD and asks for daily aspirin to prevent a first myocardial infarction. What is the best recommendation?

Choose one answer, then submit
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Sources and review status6 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 NG185: Acute coronary syndromesNational ACS antiplatelet pathway.
  • NICE NG238: CVD risk assessment and reductionAspirin is not routinely offered for primary prevention.
  • NICE TA210: Clopidogrel and modified-release dipyridamoleSecondary prevention after occlusive vascular events.
  • Ticagrelor 90 mg SmPCUK loading, maintenance and aspirin doses.
  • Prasugrel 10 mg SmPCUK PCI dosing and contraindications.
  • Clopidogrel 75 mg SmPCSyndrome-, PCI-, fibrinolysis- and age-specific loading regimens.

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
Why
Locate and treat clinically important haemorrhage.
Interpretation and limitations
Use urgent neuroimaging for focal neurology/head injury and endoscopic or interventional evaluation for significant GI bleeding.
2
Continue the nationally recommended single agent after the finite DAPT course; aspirin is generally indefinite after MI.
  • 3Address smoking, lipids, blood pressure, diabetes and rehabilitation rather than treating antiplatelets as complete prevention.
  • 4Review bleeding, adherence and the continuing indication at medication reviews.
    • 03EscalationBleeding or urgent procedureEscalationMajor bleeding, intracranial symptoms or surgery before the planned antiplatelet course is complete.+
    1. 1Resuscitate, identify the bleeding site, send FBC/coagulation/renal testing and obtain urgent specialist haemostasis support.
    2. 2Balance immediate bleeding control against stent thrombosis risk using the exact PCI date and indication.
    3. 3For non-emergency procedures, coordinate interruption and restart with the proceduralist and interventional cardiologist.
    4. 4After haemostasis, restart necessary antithrombotic treatment at the earliest safe time through a documented specialist plan.

    Contraindicated with previous stroke/TIA or active bleeding; generally not recommended from age 75; higher bleeding risk at low body weight.