Secondary Prevention of Coronary Heart Disease and Stroke - Antiplatelet Guideline

The following patients should have antiplatelet therapy for life (unless they develop an indication for anticoagulation):

• CHD (angina, acute coronary syndrome, post-CABG)
• Thrombotic stroke or transient ischaemic attack (TIA). See the Secondary Prevention of Stroke and Transient Ischaemic Attack guideline).
• Peripheral arterial disease (intermittent claudication or post-graft)

Aspirin oral 75mg daily (dispersible tablet) is the agent of choice (but see separate guidance here for stroke and TIA). Enteric coated aspirin does not reduce gastrointestinal (GI) symtoms. Only if aspirin is contraindicated or the side effects are intolerable (see section below 'Contraindications to aspirin') should clopidogrel oral 75mg daily be used instead.

Caution with all antiplatelets - ideally blood pressure should be under control (<150/90mmHg) prior to commencing any antiplatelet agent, and certainly systolic <180mmHg.

Combination antiplatelet regimens

Table 1 – Antiplatelet dual therapy regimens

Notes

• Coronary artery stents: Do not discontinue antiplatelet dual therapy sooner than the recommended durations in Table 1 without prior discussion with the patient's interventional cardiologist (details can be found on patient's clopidogrel / ticagrelor card). If an invasive procedure is required, and cannot be delayed till end of clopidogrel / ticagrelor prescription, consult patient's interventional cardiologist for individual action plan.
• The duration of dual antiplatelet therapy may be extended at the discretion of the interventional cardiologist depending on the extent of disease.
• If there is significant carotid stenosis following acute stroke or TIA, patient may be considered for combination aspirin and clopidogrel, at the discretion of a stroke consultant, whilst awaiting carotid surgery.

Combination warfarin and antiplatelet agents

This combination is associated with a significantly higher major haemorrhage complication rate than either agent alone, without offering any proven benefit in reducing ischaemic or thromboembolic events (except in patients with metallic prosthetic heart valves).

Patients on warfarin who develop an indication for an antiplatelet agent (e.g. thrombotic stroke, ACS)

Low thrombosis risk patients (e.g. moderate risk atrial fibrillation (AF), deep vein thrombosis (DVT) >3 months previously) who develop an indication for dual antiplatelet therapy (e.g. AF patient requiring coronary stent) should stop warfarin or receive triple therapy for as short a time as possible. Consideration should be given to the use of a bare metal stent.

High thrombosis risk patients (e.g. high risk AF, recent venous thromboembolism) developing an ACS, require specialist advice and be considered for triple therapy.

Patients on antiplatelet agents who develop an indication for Warfarin therapy (e.g. AF, DVT)

In patients with stable vascular disease, on a single antiplatelet agent, this agent should be discontinued for the duration of warfarin therapy.

In patients with unstable vascular disease (e.g. recent ACS or stent) receiving dual antiplatelet therapy warfarin should be commenced cautiously with close monitoring and discontinuation of aspirin +/- ticagrelor / clopidogrel earlier than planned should be discussed with an interventional cardiologist.

It is accepted that some high thrombotic risk patients, with low inherent bleeding risk, may merit short-term triple therapy, however each case should be considered individually with a full risk:benefit assessment.

Troponin positive ACS patients admitted on antiplatelet therapy

• On aspirin monotherapy – add ticagrelor oral 90mg twice daily as per ACS protocol.
• On clopidogrel monotherapy due to aspirin GI intolerance:
  • Switch to aspirin oral 75mg daily and ticagrelor oral 90mg twice daily
  • Add in PPI
• On clopidogrel monotherapy due to previous TIA / CVA:
  • Add aspirin oral 75mg daily
  • Stop aspirin after dual antiplatelet therapy course is complete.
• On aspirin and clopidogrel after previous ACS admission – switch clopidogrel to ticagrelor oral 90mg twice daily.

Contraindications to aspirin

These are rare, but include aspirin allergy (aspirin-induced angioedema, asthma or skin rash).

Relative contraindications for all antiplatelet agents (only prescribe on expert advice):

• Recent GI bleed
• Proven active peptic ulcer disease
• Breast feeding
• Haemophilia or other bleeding disorder

GI symptoms and use of aspirin

• In patients with a history of bleeding peptic ulcer disease the combination of aspirin + PPI is safer than clopidogrel alone (for secondary prevention).
• In patients developing GI symptoms after starting aspirin follow the algorithm below.

Patients developing GI symptoms after starting aspirin