Clinic: A Major Advance in Management of Transient Ischemic Attacks

Front Neurol Neurosci. Basel, Karger, 2014, vol 33, pp 30-40 (DOI: 10.1159/000351890)

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TIA Clinic: A Major Advance in Management of Transient Ischemic Attacks

Philippa Lavallée · Pierre Amarenco

INSERM U-698, Department of Neurology and Stroke Center, AP-HP, Bichat-Claude Bernard Hospital, University Paris Diderot, Sorbonne Paris Cité, Paris, France

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Abstract

Patients with transient ischemic attack (TIA) are at very high risk of imminent stroke. This risk could be decreased by 80% if patients are immediately investigated and treated by stroke specialists. However, because TIA workup includes not only specialist advices but also a wide range of investigations such as brain, arterial and cardiac imaging, management of these patients in emergency required well-organized dedicated health care system, such as TIA clinics. Management of TIA patients in outpatient clinics has been shown to be safe and cost-effective avoiding full hospitalization in most of the cases.

Despite great educational efforts, stroke is still the second cause of death worldwide and is the leading cause of acquired disability. We know that the risk of stroke can be reduced by treatment of traditional vascular risk factors [1]. Among predictors of stroke, transient ischemic attack (TIA) is the most important warning sign because patients who had experienced a recent TIA are exposed to a very high risk of imminent stroke [2–4] underlining the importance of immediate assessment and treatment of these patients. Assessment of TIA patients requires diagnosis confirmation and identification of the cause in order to start effective secondary prevention to prevent a disabling vascular event. TIA identification is often difficult, and the large panel of investigations needed is nearly impossible to organize in this narrow window either for emergency department physicians in community hospital or for general practitioners (GPs), the health care providers who usually receive first call to medical attention from patients with recent TIA. Then patients are frequently sent back for outpatient investigations that will be effectively performed within one week or more. Such counterproductive pathway despite published guidelines [5–8] has several explanations; one of these is the lack of fast-track access to structure dedicated to TIA management. In the last 10 years, TIA clinics have been developed to provide immediate access to care in case of suspicion of TIA for immediate investigations and treatment. Early experiences have shown the efficacy of such pathway by reducing the 3-month risk of stroke by 80% [9, 10].

What Is the Optimum Provision of Care in TIA Clinics?

The primary objective is to diagnose and prevent recurrent stroke and other vascular events, and educate patients on vascular risk factor management. Following AHA/ASA, ESO and NICE guidelines [5–7], optimal TIA clinic service includes:

Fast Track Access

TIA management must not suffer any delay as the risk of recurrent stroke is high and imminent: 5% at 2 days [2], 8% at 7 days [4, 11], 7-12% at 30 days [3, 4, 11]. Hence, guidelines recommend immediate access to the TIA clinic for specialist assessment and treatment within 24 h of symptom onset for high-risk patients [8, 12, 13]. The NICE recommends that patients at a lower risk of recurrent stroke (such as patients with an ABCD² score <4) be evaluated within 48 h to one week [5]. However, 20% of patients with ABCD² score <4 have an ipsilateral >50% stenosis (either extra- or intracranial) or atrial fibrillation with a risk of recurrent stroke at 3 months, which is similar to patients with ABCD² score >4, and need to be urgently evaluated and treated [14].

Stroke Specialist Assessment

Experience always wins the day. The assessment of TIA patients by stroke specialists can positively impact their management by acting at various levels.

The first level, and probably the most obvious, is symptom recognition: Has this patient really had a TIA? In daily practice, even for stroke neurologists, accurate diagnosis of TIA remains frequently challenging [15, 16]. Transient symptoms are not synonymous with TIA and most of them can have non-ischemic origin (the so-called TIA mimics). Moreover, according to vascular territory, TIA can have a wide range of clinical presentations. If transient hemiplegia is usually not a big clinical solving issue, interpretation of subtle symptoms such as cognitive disorders, vertigo, diplopia, visual impairment, unsteadiness or dysarthria, which could occasionally be related to brain ischemia, is more difficult. Many studies have shown a poor agreement between referring physicians and stroke specialists for TIA diagnosis, with a false positivity rate as high as 60% [17, 18]. Evaluation of patients with transient neurological symptoms by stroke experts allows identifying stroke mimics avoiding unnecessary and costly investigations and therapies that could also have adverse effects.

Once the TIA diagnosis is confirmed or considered as possible, the next step is to determine which vascular territory was affected in order to guide further investigations and treatment. Correlating symptoms with the correct diseased artery is important, particularly when a carotid endarterectomy is considered because the benefit/risk ratio for surgery is highly dependent of the presence of recent symptoms in the territory of the stenosed vessel [19]. But it is also important in order to guide the physician in the choice of arterial investigation modalities. For example, Doppler ultrasound is less sensitive for the detection of stenosis in the posterior circulation or in intracranial artery than other arterial imaging modalities such as magnetic resonance or CT angiography (MRA, CTA) [20]. Then, facing a patient with symptoms such as diplopia and vertigo, which is highly suggestive of ischemia in the posterior circulation, a stroke expert will not be reassured by a normal cervical Duplex ultrasound, and will focus further investigations on vertebral and basilar arteries.

The next step is to identify the cause in order to guide specific secondary prevention intervention. A large variety of pathological conditions can cause cerebral ischemia, and stroke subtyping requires arterial or cardiac investigations, among others. Depending on patient characteristics, clinical presentation, and clinical findings, the physician will structure and tailor the comprehensive investigation tests but also will evaluate how urgent these tests are. A left Horner’s syndrome in a 40-year-old patient who recently had transient right hand numbness and left-sided cervical pain is almost pathognomonic of a left carotid dissection. In that case, detailed carotid artery imaging is absolutely required in emergency, such as axial sections of FAT-saturated MRI of the ipsilateral internal carotid artery beyond its origin that is the most sensitive tool to diagnose the arterial wall hematoma, which is specific to dissection, whereas cardiac investigations are unnecessary.

Moreover, vascular neurologists should work with a team of cardiologists and radiologists skilled in the field of stroke, knowing exactly what they have to look for and how to do it. Expertise and knowledge are undoubtedly helpful as we can see it in the daily practice, where cardiac, brain or arterial investigations are not so rarely incomplete or misinterpreted when performed by non-specialists.

Stroke specialists know the vascular and brain anatomy, both common and uncommon stroke etiologies and clinical presentations, and also general neurology to diagnose neurologic diseases that mimic stroke.

Investigations

Among the challenges of TIA management, the need of a relatively large panel of investigations is not the least. MR imaging of the brain within the first 24 h of symptom onset has become the gold standard [5–7] to diagnose cerebral infarction in case of transient focal neurologic deficit. A positive DWI allows reclassifying a TIA presentation into a cerebral infarction [21]. A negative DWI defines an actual TIA. MRI also distinguishes TIA from stroke mimics such as cerebral hemorrhage, and allows imaging of the vessels supplying the ischemic field. CT will be done if MRI is not available. ECG, 24-hour ECG monitoring, echocardiography and blood tests are usually necessary for stroke subtyping.

TIA clinics must provide, directly or via an efficient organized network, fast track access (sometimes immediate) to these different diagnostic tests needed to tailor treat-ment but also to help triage high-risk patients who need hospitalization for close monitoring, e.g. tight stenosis due to large artery atherosclerosis or cardiac thrombus [22], but also in less frequent disease such as non-atherosclerotic arteritis, dissection or prothrombotic states, when a specific treatment is to start without delay (e.g. endarterectomy for high grade carotid stenosis, anticoagulation in case of intracardiac thrombus). As a consequence, vascular imaging must be performed urgently, and rapid access to echocardiography (even if rarely needed in emergency) should be feasible if necessary.

Screening and treatment for vascular risk factors and coronary and/or other peripheral arterial diseases are part of services provided by TIA clinics.

Education

Education is crucial. Patients have to understand the seriousness of the disease, learn symptom recognition and what to do in case of recurrence. Importance of antithrombotic treatment and in-depth knowledge of vascular risk factors and their management are also fundamental to patient adherence and retention. A traditional outpatient GP consultation is not adapted for patient education regarding the shortness of the visit and the amount of information that has to be delivered, whereas TIA clinic environment is an ideal place to settle therapeutic educational program [23].

Network

In addition to necessary links with cardiologists and radiologists for TIA workup, TIA clinics should also facilitate access to vascular surgeon (if carotid endarterectomy is required) or endovascular therapist, but also to inpatient stroke unit if stroke unit admission is required. Telemedicine can also help diagnose TIA and guide prompt investigations in a remote area.

What Is the Ideal Setup for TIA Clinic?

Different models of service delivery have been described: outpatient setting, emergency room, dedicated hospital service for less than 24 h (day hospital). All share the same principle, according to recent guidelines [5–7]: allow TIA patients to have an urgent access to specialized stroke services. The choice between these models is largely impacted by regional, national and/or institutional differences, and, given these local specificities, are all acceptable options. No randomized trials have been performed to evaluate the benefit of TIA care provided in inpatient in comparison to outpatient settings.

Inpatient Setting

Immediate routine admission in stroke unit has been proposed as a standard care for TIA patients [24], whereas some current guidelines recommend hospitalization only for selected patients (ABCD² score ≥3; score of 0-2 and uncertainty that diagnostic workup can be completed within 2 days as an outpatient; score of 0-2 and other evidence that indicates that patient’s symptom was caused by focal ischemia) [7

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