Key Learning Points: NICE Stroke and TIA

Dr Ivan Benett Identifies Five Key Learnings for Primary Care From the NICE Guideline on Stroke and Transient Ischaemic Attack

Stroke is an acute neurological event, presumed to be vascular in origin, which causes cerebral ischaemia, cerebral infarction, or cerebral haemorrhage.¹ Around 85% of strokes are ischaemic as they are caused by the blockage of one of the cerebral arteries by a thrombus.² Ischaemic strokes are characterised by specific deficits depending on which artery is blocked. The middle cerebral artery is most commonly affected, causing hemiparesis, slurred speech, facial weakness, and sometimes dysphasia (if the dominant lobe is affected). About 15% of strokes are caused by intracranial haemorrhage.² These cause a less characteristic combination of deficits and are often more debilitating, but rapid recognition and treatment can significantly reduce disability and death.

Immediately following a stroke, part of the brain becomes infarcted and is not recoverable. Blood flow (and therefore oxygen transport) to the surrounding area, known as the penumbra, is also reduced, which can lead to hypoxic cell death. The penumbra may still be viable for several hours before becoming ischaemic but, if left untreated, can become irrecoverable too.²

A transient ischaemic attack (TIA) is a brief episode of neurological dysfunction caused by focal cerebral, spinal cord, or retinal ischaemia, without permanent infarction.³ After recovery, there is little or no evidence of ischaemia on imaging. All cases of suspected TIA should be considered as potentially high risk for full stroke; risk of stroke is about 5% within 48 hours, 8% within 1 week, 12% within 1 month, and 17% within 3 months of a TIA.²

In the UK, the annual incidence is about 2.3 per 1000 people for stroke, and about 0.5 per 1000 people for TIA.⁴

In May 2019, NICE published NICE Guideline (NG) 128 on Stroke and transient ischaemic attack in over 16s: diagnosis and initial management,¹ which updates and replaces the previous NICE guideline on stroke and TIAs.⁵ The update includes some radical changes, mostly related to inpatient and secondary care diagnosis and management. This article will focus on the recommendations that are most relevant to GPs. The secondary care changes will be briefly discussed at the end.

1. Recognise the Symptoms of Stroke and TIA Promptly

Prompt recognition of symptoms is critically important to limiting potential brain damage and subsequent disability, so suspect stroke or TIA in anyone who has sudden onset of neurological symptoms. NG128 recommends using a validated tool, such as FAST (Face, Arms, Speech problems, Time),⁶ outside hospital to screen people with sudden onset of neurological symptoms for a diagnosis of stroke or TIA.¹ NG128 highlights the need to exclude hypoglycaemia as the cause of symptoms. There are, however, other conditions that can mimic stroke, including migraine, epilepsy, sepsis, and other causes of delirium.⁷

2. Offer Aspirin for Suspected TIA, To Be Started Immediately

NICE recommends that, unless contraindicated, aspirin (300 mg daily) is offered to people who have had a suspected TIA, to be started immediately.¹ NG128 does not make specific suggestions about what treatment to offer if aspirin cannot be used.

If aspirin cannot be used, then clopidogrel may be a suitable alternative. A recent study found that dual antiplatelet therapy combining clopidogrel with aspirin, given within 24 hours after high risk TIA or minor ischaemic stroke, reduces subsequent stroke by about 20 per 1000 population, with a possible increase in moderate-to-severe bleeding of 2 per 1000 population.⁸ Authors of the study concluded that discontinuation of dual antiplatelet therapy within 21 days, and possibly as early as 10 days, of initiation is likely to maximise benefit and minimise harm.⁸ This study was not considered in the development of NG128 because it was published after the cut-off date for submission of evidence.

3. Refer People Who Have a Suspected TIA Immediately

NICE recommends that people who have had a suspected TIA are referred immediately for specialist assessment and investigation, to be seen within 24 hours of onset of symptoms.¹

In the past, risk stratification was recommended to determine the urgency of referral. However, since the risk of stroke following TIA is so great within even a few days, the NG128 guideline committee decided to recommend immediate specialist assessment. NG128 specifically recommends that scoring systems (such as ABCD2) are not used to assess risk of subsequent stroke or to inform urgency of referral.¹ This is likely to have significant resource implications, and pathways will need to developed locally by commissioners and providers.

Diagnosis of TIA should be based on clinical assessment and not on brain imaging; NG128 recommends computed tomography (CT) brain scanning is not offered to people with a suspected TIA, unless there is a clinical suspicion of an alternative diagnosis that CT could detect.¹ Magnetic resonance imaging (MRI), including diffusion-weighted and blood-sensitive sequences, can be considered after specialist assessment in the TIA clinic, to determine the location of ischaemia, or to detect haemorrhage or alternative pathologies. If MRI is performed, it should be done on the same day as the assessment.¹ NG128 also recommends urgent carotid imaging for everyone with TIA who, after specialist assessment, is considered as a candidate for carotid endarterectomy.¹

4. Offer Secondary Prevention After the Diagnosis of TIA is Confirmed

NICE recommends that secondary prevention is offered in addition to aspirin as soon as possible after the diagnosis of TIA is confirmed.¹ This includes continuing antiplatelet and statin therapy, and monitoring risk factors such as blood pressure and lifestyle.

A recent study of patients who had had a TIA or minor stroke observed a sustained risk of cardiovascular events including stroke over a period of 5 years; the rate of cardiovascular event was 6.4% in the first year and 6.4% in the 2–5 years after the initial TIA.⁹ This may have been a result of under-management due to a decrease in medication adherence as time went by. Also, of 835 active smokers (22.0% of 3801 patients) at baseline, 388 (10.2%) were still active smokers at 1 year, and 292 (7.7%) at 5 years.⁹

5. Admit People with Suspected Stroke Directly to a Specialist Acute Stroke Unit After Initial Assessment

NICE recommends that everyone with suspected stroke is admitted directly to a specialist acute stroke unit after the initial assessment, either from the community, the emergency department, or outpatient clinics.¹ This recommendation remains unchanged from the previous guideline, but carries increased importance because the interventions that are available in specialist acute stroke units can now be successful even 24 hours or more after the stroke event.

In addition, NG128 recommends that aspirin (300 mg) is offered as soon as possible, but certainly within 24 hours, to everyone presenting with acute stroke who has had a diagnosis of intracerebral haemorrhage excluded by brain imaging.¹

Recommendations for Secondary Care

The most significant new recommendations for secondary care pertain to thrombectomy, which involves the removal of the blood clot blocking the cerebral artery followed by insertion of a stent to allow reperfusion of the still viable penumbra. Refer to Box 2 for the recommendations from NG128 about thrombectomy for people with acute ischaemic stroke.¹

Recommendations for thrombolysis remain the same; alteplase is recommended within its marketing authorisation for treating acute ischaemic stroke in adults if treatment is started as soon as possible within 4.5 hours of the onset of symptoms and intracranial haemorrhage has been excluded by appropriate imaging techniques.¹

Summary

In summary, from a GP’s or first responder’s perspective the main action is to suspect a stroke or TIA in anyone who presents with new onset neurological symptoms. Clinicians should bear in mind possible alternative diagnoses, especially hypoglycaemia, seizures, sepsis, or migraine.

If a TIA is suspected, NICE recommends urgent referral for specialist assessment at a TIA clinic, to be seen within 24 hours of onset of symptoms. To enable this to happen, local arrangements and pathways will need to be developed. Aspirin should be initiated unless there are reasons not to.

If a stroke is suspected, NICE recommends direct admittance to a specialist stroke unit, even if more than 24 hours have passed since the patient was last known to be well. Here the patient will be assessed to determine whether thrombolysis is likely to improve outcomes, and optimal rehabilitation will be initiated. At this point it may still be unclear whether the patient is having a TIA or stroke. After hospitalisation, secondary prevention measures and ongoing rehabilitation should be initiated, and the psycho-social needs of the patient and their carers should be addressed.

Dr Ivan Benett

General Practitioner, Didsbury, Manchester

Member of the guideline development group for NG128