>EM Reflections January 2021: TIA Review

 

Big thanks to Dr. Paul Page for leading discussions this month.

All cases are theoretical, but highlight important discussion points.

Authored and Edited by Dr. Mandy Peach

Case

A 69 yo male presents to the ED with dizziness that was ongoing 1 hour. His symptoms began when getting up from the couch and walking to the kitchen. He felt like he was going to ‘pass out’ and ‘couldn’t walk straight’. He also describes having a headache that began around the same time, but says he has headaches from time to time and wasn’t bothered by it. After 1 hour of feeling dizzy and off balance he called EMS. His symptoms resolved en route with EMS in the ambulance.

His vitals in triage are: 128/64, HR 89, RR 16 O2 95% on RA, T 36.3 Glucose 15

The nurse hands you his medication list and ECG

The ECG indicates atrial fibrillation. This is new from his previous ECG. His medications include ramipril, metformin and atorvastatin.

You suspect a transient ischemic attack (TIA), but what other mimics are on the differential1?

 

What are some important causes of TIA to consider? What features make TIA more likely1?

You feel your patient’s abrupt inability to walk straight certainly qualifies as lack of function. The onset was abrupt and symptoms have resolved. Your patient also has new atrial fibrillation, putting them at risk.

What if the patient didn’t have new atrial fibrillation? What other symptoms/features on clinical exam could suggest an alternative cause1?

Think “TIA and”…

TIA and neck pain: cervical artery dissection

TIA and new fever or heart murmur: endocarditis

You complete your physical exam. The patient is neurologically normal including cranial nerves, motor, sensory, reflexes, cerebellar, and gait. There is no new murmur, fever or neck pain. The patient has new a fib of unknown duration that is not anticoagulated. You suspect this is the cause.

Although the patient is normal now, you do wonder if they had objective signs initially with EMS, or with the first nursing assessment. As neuros can change so quickly you review the other documented exams

Of note EMS reports a GCS of 15 and the following description of symptoms:

“off balance, requiring support to walk”

“noticeable trouble speaking with slurred speech”

“patient reports feeling dizzy”.

The symptoms resolved en route. The patient walked unassisted from the ambulance bay to triage.

Nursing notes document a normal neuro exam in triage.

Is there a timeline involved in diagnosis TIA2?

TIA is now defined as a transient episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction. The end point, stroke, is biologic (tissue injury) rather than an arbitrary timeline (≥24 hours).

Although the patient is now neurologically normal, this episode is a big red flag for stroke. To determine how urgent a work up is needed you decide to stratify the patient’s risk of stroke. The ABCD2 score likely comes to mind:

 

Is this tool accurate at predicting stroke3?

With the ABCD2 score physicians may misclassify up to 8% of patients as low risk. The sensitivity of the score for high risk patients was found to be only 31.6%3. This score also does not take into account neuroimaging findings – one study found up to 15% of patient’s with high grade carotid stenosis would be missed by using the ABCD2 score. Lastly an Australian study that used the ABCD2 score with ED patients all reported similar rates of strokes at the 30 and 90 day follow up, regardless of stratification using this tool.

Bottom line – ABCD2 is out.

So is there any tool I can use to predict risk of stroke4?

The Canadian TIA Score

This score was initially studied prospectively in over 7500 adult patients diagnosed with TIA in the ED or by a neurologist. The primary outcome was subsequent stroke in 7 days or prompt emergency carotid endarterectomy (CEA) to prevent stroke in less than 7 days. 1.4% of patients had a stroke and 1.0% had CEA in less than 7 days.

The score has recently been validated and is ready for clinical use8.

This score classifies patients as:

LOW risk: -3 to 3 points. Safely discharge following careful ED assessment with elective follow up

MEDIUM risk: 4-8 points. Undergo additional testing in the ED, have antithrombotic therapy optimized, be offered early stroke/neuro follow up

HIGH risk: ≥ 9 points. Fully investigate and manage ideally in consultation with a stroke specialist during the first ED visit.

Your patient is already at medium risk, before imaging is acquired. According to this tool your patient should be investigated with labs and imaging in the ED and offered urgent neuro follow up.

The acute nurse reminds you that it is 2330 and the CT tech leaves at midnight. You need to arrange urgent imaging – but what should you order6?

CT-angiography can be done at timing of non contrast CT and is the standard of care in neurovascular disease. It is well established that there is an association between vascular occlusion or high grade stenotic vessels and stroke recurrency and disability.

Angiography will show high grade stenotic lesions that are amendable to endarterectomy, as well as identify carotid or vertebral artery dissection as an alternative cause.

In high risk patients, CT-A should be the go to. This is based on Canadian Stroke Best Practice Guidelines.

 

Based on the Canadian TIA score my patient is medium risk. Could they still benefit from CT-A?

The Canadian TIA Score is not yet integrated with Stroke Management. According to Best Practice Guidelines high risk features are considered to be:

This patient had transient speech deficit – consider this a high risk feature and get a CT-A in your work up in the department.
You discuss this with your radiologist who agrees a CT-A is warranted.

Luckily a consultant neurologist is also on call and in house dealing with a patient in the neuro ICU. As this patient requires urgent neuro follow up he agrees to see post CT-A.

Your patient has 50% stenosis of the left vertebral artery. There is no sign of infarct or hemorrhage and no space occupying lesion.

The patient is assessed by neuro, while a trauma and STEMI roll into your department. You get back to work.

An hour later the neurologist speaks with you briefly after seeing the patient and agrees this is a TIA. Their plan is to initiate anticoagulation as they suspect a cardio-embolic source as the CT shows no infarct/dissection and the symptoms resolved within an hour. They plan to order an urgent echo and follow up with the patient this week and feel they can be discharged.

What would be a contraindication to starting anti-coagulation for A fib1?

Evidence of completed stroke on CT – these patients are started on anti-coagulation at a later date to prevent bleeding into infarct.

You wonder if the patient should be admitted as they had high risk features in their presenting TIA?

If the patient has a negative CT with no occlusion and no vessels amenable to endarterectomy then they can be discharged and followed-up within 48 hours1.

If there is an occlusion ameanable to endarterectomy, then admission is advisable. Urgent surgery can reduce the risk of stroke over 2 years from 26% to 9% (a 17% absolute risk reduction). If done within 2 weeks the absolute risk reduction is 30%1. This is generally the case for carotid stenosis.
Our patient has vertebral artery stenosis – which usually maximizes medical therapy before considering any surgical options7. If the patient had carotid stenosis, high grade stenosis of over 70% would warrant urgent consultation.

After this consideration you feel more comfortable with the plan and continue the rest of your shift.

You are reviewing the case with a student learner later in the shift and they ask what if the patient didn’t have A fib? What would have been the course of action1?

Investigations 1:
The patient would require holter and echo to assess for potential cardioembolic source from paroxysmal A fib. If admitted these would have beeen done as an inpatient. However, our patient was discharged. More urgent holter and echo is required for patients who:

“1. Patients with known heart disease including rheumatic heart disease, heart failure, severe valvular disease, severe CAD or history of MI.
2. Patients with no obvious cause of their TIA and no classic risk factors to identify an underlying cause of their TIA such as paroxysmal atrial fibrillation, severe valvular disease including endocarditis, PFO etc.”

Management 1:
Early dual antiplatelet therapy (DAPT) initiated within 24-72 hours and continued for 3 weeks decreases risk of stroke by up to 3.5% without increased risk of bleeding.

In the ED: load with ASA 160-325mg PO and Plavix 300mg PO
Discharge: on ASA 81 mg PO daily and Plavix 75mg PO daily x 3 weeks only

After the discussion with the neurologist the patient was discharged and given good advice on symptoms of CVA to return for. He left the ED.

 

1 week passes and you are working an evening shift. There is a stroke patient brought into the trauma bay to be urgently seen – you recognize the same 69 yo male you saw a week earlier with a TIA. On evaluation the patient has symptoms of a posterior circulation stroke. He is slightly dysarthric but can get out some slurred speech. You review his medication list and there is no anti-coagulant. You confirm with the patient he did not start any new medications after leaving the ED a week ago. When asked why he didn’t fill the prescription from the neurologist he communicates that he did not receive one.

What is the risk of stroke following TIA8?
Up to 10% of patients with TIA will have a CVA in 7 days, up to 12% in 90 days.

 

Patients in the ED are our patients, even when evaluated by a consultant and deemed well enough for discharge. In this situation confirming with the consultant who will be providing the prescription as well as confirming the patient has one in hand before leaving the department would have greatly benefited the patient.

 

 

References and further reading:

Helman, A, Himmel, W, Dushenski, D. TIA Update – Risk Stratification, Workup and Dual Antiplatelet Therapy. Emergency Medicine Cases. November, 2018. https://emergencymedicinecases.com/tia-update/. Accessed Feb 9, 2021

Furey & Rost. (2020). Initial evaluation and management of transient ischemic attack and minor ischemic stroke. Uptodate. https://www.uptodate.com/contents/initial-evaluation-and-management-of-transient-ischemic-attack-and-minor-ischemic-stroke?search=tia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H3011236877. Accessed Feb 9, 2021

Long. Updates on TIA. emDocs. April 2016. http://www.emdocs.net/8538-2/. Accessed Feb 9, 2021

Helman, A. Morgenstern, J. Klaiman, M. Sayal, A. Perry, J, Reid, S. Rezaie, S. EM Quick Hits 18 – Conservative Management Pneumothorax, Microdosing Buprenorphine, Practical Use of CRITOE, Canadian TIA Score, Pediatric Surviving Sepsis Guidelines, Safety of Peripheral Vasopressors. Emergency Medicine Cases. May, 2020. https://emergencymedicinecases.com/em-quick-hits-may-2020/. Accessed Feb 10, 2021.

https://emergencymedicinecases.com/wp-content/uploads/2018/11/Canadian-Stroke-Guidelines-summary-2018-CJEM-1.pdf

American Heart Association (2018). Role of Brain and Vessel Imaging for the Evaluation of Transient Ischemic Attack and Minor Stroke. Stroke. Vol 49 (7) pg 1791-1795

Furie. (2019). Secondary prevention for specific causes of ischemic stroke and transient ischemic attack. Uptodate. https://www.uptodate.com/contents/secondary-prevention-for-specific-causes-of-ischemic-stroke-and-transient-ischemic-attack?sectionName=LARGE%20ARTERY%20DISEASE&search=tia&topicRef=1123&anchor=H2&source=see_link#H3. Accessed Feb 10, 2021

Perry et al. (2021). Prospective validation of Canadian TIA Score and comparison with ABCD2 and ABCD2i for subsequent stroke risk after transient ischaemic attack: multicentre prospective cohort study. BMJ 2021; 372:n49.

 

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