Secondary prevention after ischaemic stroke or TIA

01Role and principlesWho benefits and the main preventive aims.

A recurrent stroke may be prevented only if the likely cause is identified. Review the clinical territory, brain infarct distribution, intra- and extracranial vessels, ECG and rhythm monitoring, cardiac structure where indicated, vascular risk factors and unusual causes suggested by age or context. Large-artery atherosclerosis, small-vessel disease, atrial fibrillation, cervical dissection, antiphospholipid syndrome and paradoxical embolism have different treatment implications. The label cryptogenic should follow an adequate, documented investigation rather than incomplete testing.

Antithrombotic selection is central. Antiplatelets reduce recurrent events in non-cardioembolic disease, with brief dual treatment considered early for selected minor stroke or high-risk TIA under a stroke protocol before transition to monotherapy. Atrial fibrillation usually requires a direct-acting oral anticoagulant unless a mechanical valve, moderate-to-severe mitral stenosis, renal limitation or another factor changes the choice. Start timing after infarction is individualised by severity, imaging, haemorrhagic transformation and embolic risk; do not use a rigid rule without reviewing current guidance.

Risk-factor care should be measurable. Record a blood-pressure plan, lipid baseline and percentage non-HDL reduction, HbA1c where relevant, smoking treatment and activity goals. Check whether medicines are affordable, understood and practically available, and simplify the regimen where possible. Selected procedures include carotid endarterectomy for recent ipsilateral symptomatic stenosis and patent foramen ovale closure after rigorous multidisciplinary attribution in a carefully selected younger patient. Follow-up should verify completion rather than merely making referrals.

Key points

Secondary prevention begins immediately but must follow mechanism: non-cardioembolic disease usually needs antiplatelet therapy, whereas atrial fibrillation generally needs oral anticoagulation once safe.
Clopidogrel 75 mg once daily is a common long-term first-line antiplatelet after non-cardioembolic ischaemic stroke; short dual antiplatelet courses are reserved for selected minor stroke or high-risk TIA protocols.
Do not combine long-term anticoagulation with an antiplatelet solely because a patient has had a stroke; use overlap only for a separate, time-limited cardiovascular indication after specialist review.
Offer high-intensity statin treatment, usually atorvastatin 80 mg daily, for established cerebrovascular disease unless interactions, adverse-effect risk or preference support a lower dose.
Treat blood pressure after the acute phase with an individualised regimen, checking postural symptoms, renal function and adherence rather than reacting to one ward measurement.
Urgently image the carotids after a compatible retinal or non-disabling hemispheric event and refer recent symptomatic 50–99% NASCET stenosis for time-critical endarterectomy assessment.
Investigate occult atrial fibrillation with monitoring proportionate to an embolic phenotype; a normal admission ECG or pulse does not exclude paroxysmal AF.
Smoking cessation, diabetes care, physical activity, diet, weight, sleep and medicine adherence contribute materially, while rehabilitation and prevention should be planned together rather than sequentially.

02Assessment and patient selectionRisk features, eligibility and important cautions.

Large-artery pattern

Recurrent events in one arterial territory, border-zone infarcts or an ipsilateral stenosis suggests atherosclerotic source, but the lesion must plausibly match the clinical side and territory.

Cardioembolic pattern

Infarcts in multiple territories, cortical emboli, atrial fibrillation, left atrial enlargement or recent myocardial injury increases the probability of a cardiac source.

Small-vessel pattern

A lacunar syndrome with a small deep infarct and longstanding hypertension or diabetes supports arteriolar disease, although competing embolic mechanisms still require proportionate assessment.

Unusual-cause signal

Young age, venous thrombosis, miscarriage, inflammatory symptoms, cancer, neck pain or a strong family history should broaden testing beyond routine atherosclerotic risk.

Medicine failure versus non-adherence

A recurrent event while a drug is listed may reflect missed doses, wrong dosing, interactions or a changed mechanism rather than pharmacological resistance.

Bleeding vulnerability

Prior intracranial bleed, frailty, renal impairment, falls, uncontrolled hypertension and interacting medicines modify but do not automatically eliminate antithrombotic benefit.

Red flags requiring action

Any recurrent focal neurological symptom is a new emergency assessment, not an issue to save for the next prevention clinic.
Recent symptomatic severe carotid stenosis has a narrow time window for maximum surgical benefit and needs immediate vascular-stroke coordination.
Melena, haematemesis, symptomatic anaemia, sudden severe headache or new neurological decline while on antithrombotics requires urgent bleeding assessment.
Uncontrolled severe hypertension, rapidly changing renal function or marked thrombocytopenia should trigger prompt treatment and antithrombotic safety review.
Pregnancy, mechanical heart valve, antiphospholipid syndrome or active cancer changes standard antithrombotic choices and warrants specialist input.

03Baseline assessmentMeasurements that guide the plan and track progress.

Investigation order

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
Brain and arterial imaging reviewFirst step
Why
Define infarct distribution and detect carotid, vertebral or intracranial disease that explains the event and may require intervention.
Interpretation and limitations
Match side, territory and stenosis method; incidental atherosclerosis should not obscure atrial fibrillation or another more plausible embolic mechanism.
02
ECG and ambulatory rhythm monitoring
Why
Detect sustained or paroxysmal atrial fibrillation that changes antiplatelet therapy to anticoagulation.
Interpretation and limitations
Monitoring duration depends on event phenotype and initial findings; longer monitoring increases yield, but detected episodes still require clinical attribution and stroke-specialist review.
03
Lipid profile and non-HDL cholesterol
Why
Establish treatment baseline, quantify response and identify severe or familial dyslipidaemia.
Interpretation and limitations
Assess adherence and aim for the current NICE secondary-prevention reduction target; add-on therapy may be needed if maximal tolerated statin is insufficient.
04
Blood pressure assessment
Why
Identify sustained hypertension and guide safe treatment after the hyperacute period.
Interpretation and limitations
Use standardised clinic and, where useful, home or ambulatory readings; postural decline and bilateral critical carotid disease may require individual targets.
05
Glucose and HbA1c
Why
Diagnose diabetes or assess glycaemic control as a modifiable vascular risk factor.
Interpretation and limitations
Avoid both chronic undertreatment and hypoglycaemia; choose targets and agents around comorbidity, frailty, renal function and cardiovascular benefit.
06
Selective echocardiography and shunt assessment
Why
Identify an actionable cardiac source such as ventricular thrombus, valve disease or a potentially causal patent foramen ovale.
Interpretation and limitations
A PFO is common and closure requires exclusion of stronger causes plus multidisciplinary assessment of anatomy, age and event type; a bubble study is not a universal screen.
07
Full blood count, renal and liver function
Why
Assess antithrombotic safety, dose selection and competing haematological or systemic causes.
Interpretation and limitations
Trend haemoglobin, platelets and renal function and respond to unexplained change; normal baseline tests do not replace later DOAC or statin monitoring.

04InterventionsLifestyle, treatment and escalation options.

01PLATELETNon-cardioembolic preventionFirst stepStroke assessment identifies atherosclerotic or small-vessel disease without a cardioembolic indication for anticoagulation.

1Confirm haemorrhage has been excluded and review whether a specialist-defined brief dual antiplatelet course is indicated for an early minor event.
2Transition to the recommended long-term single antiplatelet, commonly clopidogrel, and document the reason and intended duration.
3Assess bleeding, full blood count, gastroprotection needs, interactions, adherence and any planned invasive procedure.
4Treat lipids, blood pressure, diabetes and smoking concurrently and reconsider mechanism if another event occurs despite confirmed adherence.

02AFAtrial fibrillation after strokeKnown or newly detected atrial fibrillation is considered the likely embolic mechanism.

1Review infarct size, neurological severity, follow-up imaging, haemorrhagic transformation, renal function and competing bleeding risks with the stroke team.
2Choose the anticoagulant and start date using current stroke and AF guidance; avoid automatic immediate treatment after a large infarct or unnecessary prolonged delay after a small stable event.
3Stop antiplatelet therapy unless another explicit cardiovascular indication justifies overlap and document the review date for any combination.
4Monitor renal function, haemoglobin, adherence, bleeding and drug interactions and reassess dose after weight, age or renal change.

03CAROTIDSymptomatic carotid stenosisA recent ipsilateral retinal or hemispheric TIA or non-disabling stroke is linked to extracranial carotid narrowing.

1Start immediate best medical treatment and obtain reliable urgent carotid imaging reported with the stenosis measurement method.
2Refer 50–99% NASCET stenosis for urgent endarterectomy assessment when the patient is clinically suitable, aiming for intervention within the nationally specified timescale.
3AlternativeReview brain infarct size, disability, anatomy, perioperative risk and alternative mechanisms in the joint stroke and vascular decision.
4Continue antithrombotic, statin, blood-pressure and smoking treatment before and after surgery with clear surveillance responsibility.

04CRYPTICNo cause identified initiallyRoutine evaluation has not established a convincing stroke mechanism.

1Recheck that brain and complete arterial imaging, medication history and sufficient rhythm monitoring have actually been completed and interpreted together.
2Tailor longer rhythm monitoring, echocardiography, malignancy or thrombophilia investigation to the infarct pattern, age and clinical clues rather than ordering broad panels.
3Use antiplatelet treatment for an embolic stroke of undetermined source unless a proven anticoagulation indication emerges; empirical DOAC therapy is not routine.
4Review the diagnosis over time because later atrial fibrillation, cancer or inflammatory disease may reclassify both cause and prevention.

05Medicines and treatment safetyRegimens, contraindications and review points.

Inhibits platelet aggregation and is commonly the preferred long-term antiplatelet after ischaemic stroke or TIA without atrial fibrillation.

Clopidogrel

Use 75 mg orally once daily for long-term non-cardioembolic secondary prevention when selected; any loading dose or short dual regimen follows the acute stroke protocol.

Review active bleeding, blood dyscrasia, hepatic impairment, interacting medicines and surgery; do not combine indefinitely with aspirin or anticoagulation without a defined indication.

Prevents recurrent cardioembolic stroke when atrial fibrillation is the indication and post-infarct timing is considered safe.

Apixaban

For eligible non-valvular atrial fibrillation, use 5 mg orally twice daily, reducing to 2.5 mg twice daily only when the authorised dose-reduction criteria are met.

Verify renal function, age, weight, interactions, adherence and bleeding; it is not suitable for a mechanical valve and dose reduction must not be improvised.

Lowers atherogenic cholesterol and recurrent vascular event risk after ischaemic stroke or TIA.

Atorvastatin

Offer 80 mg orally once daily for secondary prevention, selecting a lower dose when interactions, adverse-effect risk or informed patient preference requires it.

Check baseline liver tests and interacting medicines, assess unexplained muscle symptoms and follow pregnancy and breastfeeding restrictions in current product guidance.

Sustained blood-pressure reduction substantially lowers recurrent stroke risk after the unstable hyperacute phase.

Antihypertensive therapy

Use a guideline-based individual regimen, often combining an ACE inhibitor or ARB with a calcium-channel blocker or thiazide-like diuretic, titrated to measured pressure and tolerance.

Check postural symptoms, electrolytes, renal function, frailty and carotid perfusion concerns; avoid abrupt excessive reductions and observe medicine-specific contraindications.

06Targets, monitoring and follow-upResponse, safety and longer-term review.

Measure clinic and, when useful, home blood pressure until stable, including standing pressure in older or symptomatic patients.
Repeat lipids and liver tests at the current NICE interval after statin initiation or intensification and document percentage non-HDL reduction.
For antiplatelet or anticoagulant therapy, review bleeding, adherence, over-the-counter NSAIDs, haemoglobin and upcoming procedures at each structured review.
For DOACs, calculate renal function using the product-relevant method and increase monitoring frequency with older age, frailty or intercurrent illness.
Track HbA1c, smoking status, activity, weight, diet and alcohol as specific goals rather than generic lifestyle advice.
Confirm that carotid intervention, extended rhythm monitoring or cardiac testing was completed and that results changed the documented plan when appropriate.
Ask about recurrent focal symptoms and route any new episode to emergency services rather than altering antithrombotics remotely.

07Special situationsVariants, exceptions and circumstances that change the usual approach.

Mechanism chooses antithrombotic

An antiplatelet and an anticoagulant are not interchangeable stronger and weaker versions; they target different dominant thrombotic mechanisms.

Short dual means short

Early dual antiplatelet benefit in selected minor events must be balanced against rising bleeding risk and followed by planned monotherapy.

PFO can be incidental

Because patent foramen ovale is common, closure follows causal assessment and exclusion of atrial fibrillation and arterial disease rather than the bubble-study result alone.

Dose accuracy prevents both harms

Unjustified DOAC underdosing permits embolism, while failure to reduce when authorised criteria are met increases bleeding; use the actual product rules.

Carotid benefit is time dependent

A technically suitable operation delayed for weeks may prevent less recurrent stroke than one delivered promptly after a stable non-disabling event.

Prevention includes access

A sophisticated plan fails if aphasia, cognition, cost, packaging or fragmented prescribing prevents the patient from taking treatment correctly.

08Common pitfallsFrequent interpretation and management errors.

01
Do not prescribe anticoagulation for a non-cardioembolic stroke merely because it seems more powerful than antiplatelet therapy.
02
Do not leave aspirin and clopidogrel together indefinitely after a short acute regimen unless another reviewed indication exists.
03
Do not combine a DOAC with an antiplatelet without documenting the separate indication, intended duration and bleeding review.
04
Do not reduce a DOAC dose because of age alone when the authorised multi-factor criteria are not met.
05
Do not call a stroke cryptogenic before reviewing arterial imaging, rhythm monitoring and the infarct pattern.
06
Do not allow symptomatic carotid disease to sit on a routine referral pathway or report stenosis without the measurement convention.
07
Do not give lifestyle leaflets without measurable follow-up of pressure, lipids, smoking and medicine access.