Lucan · Conditions

Transient ischaemic attack

Australian guidance: Stroke Foundation TIA Guidelines + eTG Neurology

1. Definition and epidemiology

A transient ischaemic attack (TIA) is a focal neurological deficit caused by transient focal ischaemia that fully resolves, by convention within 24 hours and in most cases within 60 minutes, without evidence of acute infarction on diffusion-weighted MRI. TIA must be managed as a time-critical emergency equivalent to completed stroke: the guideline makes a strong recommendation that patients with suspected TIA receive urgent specialist assessment and commence secondary prevention therapy urgently. (Corrected 2026-09-20, dsc: the previous text carried Australian incidence and 90-day recurrence figures, and a first-48-hours risk claim, none of which appear in the captured guideline.)

2. Pathophysiology

TIA shares the same upstream mechanisms as ischaemic stroke (Robbins Ch 28). The dominant pathway is arterio-arterial embolism: atherosclerotic plaque in large vessels (internal carotid, vertebral, aortic arch) fissures or erodes, exposing subendothelial collagen and triggering platelet adhesion. The resulting thrombus embolises distally, transiently occluding a penetrating artery or cortical branch. The second major mechanism is cardioembolism from intracardiac thrombus, most commonly secondary to atrial fibrillation (AF), where stagnant flow in the left atrial appendage promotes coagulation cascade activation and fibrin-rich clot formation. Small vessel lipohyalinosis caused by chronic hypertension produces lacunar TIA through in situ penetrating artery occlusion. In all three subtypes, the territory is rendered transiently ischaemic but not infarcted because spontaneous thrombolysis or collateral flow restores perfusion before irreversible neuronal death, which is what distinguishes TIA from completed stroke at the clinical level.

3. Clinical presentation and diagnostic criteria

TIA presents as sudden onset focal neurological symptoms corresponding to a specific vascular territory. Anterior (carotid) circulation TIA produces contralateral limb weakness or sensory loss, aphasia, or monocular visual loss (amaurosis fugax, a curtain descending over one eye). Posterior (vertebrobasilar) circulation TIA produces diplopia, ataxia, vertigo with other brainstem features, bilateral limb weakness, or bilateral visual field loss. Critically, symptoms are negative (loss of function: weakness, numbness, blindness, dysphasia) rather than positive (tingling spreading from fingertips to face suggests migraine aura rather than TIA). Diagnosis remains clinical because by the time of assessment, the deficit has usually resolved. The ABCD2 score (Age, Blood pressure, Clinical features, Duration, Diabetes) has historically been used to risk-stratify TIA but the Stroke Foundation Guidelines (June 2025) recommend against using ABCD2 in isolation as it may delay recognition of AF and symptomatic carotid stenosis in some patients.

4. Investigations and AU-specific cutoffs

All patients with suspected TIA require urgent assessment. The Stroke Foundation Clinical Guidelines (June 2025) provide the following AU-anchored investigation sequence:

Brain imaging: MRI is preferred over non-contrast CT as it is more sensitive and specific for TIA; however, urgent non-contrast CT is acceptable where MRI is not immediately available. The purpose is to exclude intracranial haemorrhage and stroke mimics (including hypoglycaemia, which should prompt an immediate bedside blood glucose).

Vascular imaging: All patients with anterior circulation TIA should undergo carotid imaging with CT angiography (aortic arch to cerebral vertex), carotid Doppler ultrasound, or MR angiography. Carotid imaging should be performed at initial assessment and must not be delayed beyond 2 days. Significant ipsilateral carotid stenosis (70 to 99% by NASCET criteria) requires urgent surgical referral.

Cardiac investigations: ECG should be performed at initial assessment for all TIA patients to detect AF. Prolonged cardiac monitoring (Holter, external loop recorder, or implantable cardiac monitor) is indicated where embolic source remains uncertain after initial workup. Echocardiography is indicated based on individual clinical factors, with transoesophageal echocardiography preferred where valvular or left atrial pathology is suspected.

Bloods: Full blood count, coagulation screen, HbA1c, fasting lipids, electrolytes, and renal function. An LDL cholesterol level is required to guide statin titration with a target of less than 1.8 mmol/L for atherosclerotic TIA.

5. Management

TIA management centres on emergency risk stratification, secondary stroke prevention initiated on the same day, and urgent specialist referral.

Triage: Patients with symptoms still present or fluctuating at time of assessment should be managed as having an acute stroke, with immediate referral to an emergency department for reperfusion workup. Patients whose symptoms have fully resolved should still be assessed urgently, as the Stroke Foundation (June 2025) makes a strong recommendation that all suspected TIA patients receive urgent clinical assessment given the concentration of stroke risk in the first 48 hours. In Australian primary care settings, TIA electronic decision support tools improve triage accuracy where available.

Antiplatelet therapy: Once haemorrhage is excluded on brain imaging, antiplatelet therapy should be commenced as soon as possible. For minor ischaemic stroke or high-risk TIA, aspirin plus clopidogrel should be started within 24 hours and continued for the first three weeks to prevent recurrence, then stepped down to monotherapy for long-term use. Dual antiplatelet therapy beyond three weeks is not recommended for secondary prevention of cerebrovascular disease in the absence of acute coronary disease or recent coronary stenting.

Anticoagulation for AF: Where AF is identified, anticoagulation should begin once CT or MRI has excluded intracranial haemorrhage. Direct oral anticoagulants (DOACs) are preferred over warfarin for non-valvular AF with adequate renal function. Warfarin (target INR 2.5, range 2.0 to 3.0) remains appropriate for valvular AF or renal impairment. Antiplatelet agents must not be used instead of anticoagulation in patients with AF.

Blood pressure: All patients with a clinic blood pressure above 140/90 mmHg should have antihypertensive therapy initiated or intensified before or soon after discharge. Preferred agents include ACE inhibitors, angiotensin II receptor blockers, calcium channel blockers, or thiazide diuretics. Beta blockers should not be used as first-line agents unless ischaemic heart disease is present.

Carotid surgery: Carotid endarterectomy is recommended for recent (under 3 months) non-disabling carotid territory ischaemic stroke or TIA with ipsilateral stenosis of 70 to 99% (NASCET criteria), where a specialist team with audited practice has a perioperative stroke and death rate below 7%. For symptomatic stenosis of 50 to 69%, endarterectomy can be considered in selected patients where the centre rate is below 3%. Surgery should be performed as soon as possible, ideally within two weeks of the event. Endarterectomy is preferred to carotid stenting because of lower perioperative stroke risk, with stenting reasonable in unfavourable anatomy, restenosis after endarterectomy, previous neck radiotherapy, or in patients under 70 with an experienced proceduralist. Endarterectomy or stenting should not be performed for asymptomatic carotid stenosis, and all patients with carotid stenosis should receive intensive vascular secondary prevention therapy. (Corrected 2026-09-20, dsc: the previous text carried a single 6% threshold, which is not what the guideline states.)

Lifestyle and patient education: Patients and carers must receive counselling on smoking cessation, exercise, diet, diabetes management, recognition of stroke warning signs, driving restrictions pending specialist review, and when to call 000.

6. Pharmacology and AU PBS notes

Antiplatelet agents for TIA secondary prevention:

Aspirin 100 to 150 mg orally, daily (PBS listed, no streamlined code required for this indication).

Clopidogrel 75 mg orally, daily (PBS streamlined code 1213 for secondary prevention after ischaemic stroke or TIA). Used as monotherapy where aspirin is not tolerated, or in combination with aspirin for the first three weeks after high-risk TIA or minor stroke.

Modified-release dipyridamole 200 mg combined with low-dose aspirin twice daily (Asasantin SR) is an alternative long-term option listed on the PBS (streamlined code 8161).

For AF: DOACs are PBS listed for non-valvular AF. Apixaban (Eliquis) 5 mg twice daily, rivaroxaban (Xarelto) 20 mg daily with evening meal, and dabigatran (Pradaxa) 150 mg twice daily (110 mg twice daily in those aged over 75 or with renal impairment) are all appropriate. AU brand names reflect the above generic to brand mapping.

Statin: High-potency statin therapy regardless of baseline lipid levels. Rosuvastatin 20 to 40 mg daily or atorvastatin 40 to 80 mg daily. LDL target below 1.8 mmol/L for atherosclerotic TIA. PBS Authority prescription required for high-dose statin beyond standard formulary thresholds.

ACE inhibitor or ARB: Perindopril (Coversyl) or ramipril (Tritace) are commonly used AU brands. Dose titrated to maximum tolerated.

7. Complications and monitoring

The principal complication of TIA is subsequent ischaemic stroke, with risk highest in the first 48 hours and substantially mitigated by urgent treatment initiation. Antiplatelet and anticoagulant therapy carry major bleeding risk, particularly gastrointestinal; baseline FBC, renal function, and coagulation should be checked and reviewed at 6 to 12 monthly intervals.

DOACs require at least annual renal and hepatic function monitoring, as impaired clearance necessitates dose reduction or switch to warfarin. Warfarin users require INR monitoring with a target range of 2.0 to 3.0.

Blood pressure monitoring at each visit targets systolic below 130 mmHg long term. Lipid monitoring confirming LDL below 1.8 mmol/L is recommended 6 to 12 weeks after statin initiation or dose change.

Carotid endarterectomy patients require perioperative monitoring for wound haematoma, cranial nerve injury, and perioperative stroke, which is the primary surgical quality metric in AU centres.

Annual influenza and pneumococcal vaccination are recommended for all patients with established cerebrovascular disease per eTG secondary prevention guidance.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.