tia

transient ischaemic attack (TIA)

transient ischaemic attack (TIA)

introduction

median age for TIA is 70yrs with males:females ratio 1:1
annual stroke risk after a TIA = 1-15%
almost half of subsequent strokes occur in the first month - many within the first 2 days.

TIA - to admit or Mx as outpatient?

most current thinking is that TIA patients should be admitted under a neurology unit and have early investigations and lifestyle modifications to prevent stroke as risk of subsequent stroke within 28 days appears to be higher in TIA patients discharged from ED compared to admitted patients.
currently admitted TIA patients have a median LOS in hospital of ~5-6 days and although their 28day stroke rates are improved, it seems their 1 year stroke rates are no better than those who are not admitted for their TIA.
this 5-6 day LOS in hospital further contributes to bed access block and increased morbidity and mortality for those non-TIA patients not so lucky to be able to get a hospital bed in a timely manner.

why should hospital admission prevent early stroke?

postulated possibilities include:
- early comprehensive investigation of preventable factors:
  - carotid doppler USS
  - echocardiography for those in AF or with cardiac valve pathology
- early initiation of stroke prevention measures:
  - investigation-guided antithrombotic choices - aspirin vs warfarin
  - treatment of vascular risk factors
  - intensive lifestyle modification

why do admitted TIA patients have similar 1 yr stroke rates to non-admitted patients?

postulated possibilities include:
- suboptimal Mx in some of the admitted patients
- failure to maintain secondary prevention strategies after the 1st month
- a catching up of care of the discharged TIA patient
- a higher proportion of TIA mimics amongst the discharged TIA patients
- post-TIA stroke mostly occurs in the 1st 28 days, and rates thereafter are comparable whether admitted initially or not.

can we reduce subsequent stroke risk without resorting to inpatient care?

it would seem 28 day stroke risk is NOT improved by admission in the low risk group (ABCD scores < 4)
TIA pathways to ensure timely Ix and follow up of TIA from the ED.
outpatient TIA clinics which could provide follow up of Ix and commence risk reduction strategies within 2 days of TIA
these need further research

current principles of Mx of TIA in the ED

rapid blood sugar to exclude hypoglycaemia
oxygen if hypoxic
FBE, U&E, glucose, (clotting if on warfarin or in AF)
ECG
early CT scan brain to exclude haemorrhage or other pathology
- if the non-contrast CT scan of the brain is normal, there is no need to proceed to either a contrast CT scan or MR angiogram. MRI DW is the preferred neuroimaging technique if the non-contrast CT scan is normal as it has the greatest sensitivity for minor ischaemic injury which informs both diagnosis and prognosis.
- arterial calcification on CT
  - arterial calcification in patients increases the risk of atherosclerotic stroke independent of age, sex, and atrial fibrillation
  - carotid siphon calcification on CT may be a cause of branch atheromatous disease (BAD) in intracranial artery atherosclerosis and progressive disease resulting in lacunar infarcts, especially if calcification density is greater than 557Hu and intracranial stenosis is > 50% and intracranial calcification is associated with the early progression or recurrence of stroke, coronary events, vascular deaths, and hemorrhagic transformation in patients with non-cardioembolic stroke ¹⁾
  - absence of calcification in the carotid artery siphon on CT has high negative predictive value for carotid artery stenosis in patients with suspected stroke ²⁾
  - vertebrobasilar calcification in patients with ischemic stroke is a valid predictor for stroke recurrence and acute vascular disease
gentle BP control if severely hypertensive
discuss with neurology:
- aspirin (acetylsalicylic acid) Rx
- warfarin Rx if in AF
- admission to ED Short Stay Unit under a TIA pathway, or, under neurology or dedicated stroke unit if available
- early carotid doppler USS:
  - patients with sonographic stenosis of 50-69% generally require further evaluation such as CT angiography or MRA
    - those with stenosis on CT angio or MRA of 80% or more generally should be considered for Rx as below.
  - patients with sonographic stenosis of 70% or more generally should be considered for either carotid endarterectomy (esp. younger patients) or carotid stenting (older patients with IHD)³⁾
  - carotid endarterectomy is best performed within 2 weeks of a non-disabling stroke or TIA.
  - risk of stroke, death or myocardial infarction was increased in the patients undergoing stenting vs endarterectomy ⁴⁾
- early echocardiogram if AF or valvular heart disease
- early neurology review (within a week) - eg. TIA outpatient clinic if discharged home following carotid doppler.