I just finished listening to the podcast and reviewing the show notes of the awesome Ep 117 TIA Update – Risk Stratification, Workup and Dual Antiplatelet Therapy November, 2018 from Emergency Medicine Cases.
Also, please see the References (1) to (9) below in Additional Resources. These references compliment the podcast and show notes.
The show notes links above are all you need but I placed excerpts from the podcast to help me remember the points. So here are some excerpts from the podcast:
This is Part 1 of EM Cases two part podcast on TIA and Stroke with Walter Himmel and David Dushenski – TIA Update – Risk Stratification, Workup and Dual Antiplatelet Therapy.
Much has changed in recent years when it comes to TIA risk stratification, workup and antiplatelet therapy. In this podcast we use the overarching theme of timing to elucidate how to distinguish true TIA from the common TIA mimics, the importance of timing in the workup of TIA, why the duration of therapy with dual antiplatelet therapy and timing of starting anticoagulation in patient with atrial fibrillation, contributes to the difference between preventing catastrophic strokes and causing intracranial hemorrhage. Remember that stroke is a leading cause of adult disability and is the third leading cause of death in Canada. It’s time we paid more attention to TIA…
This is Part 1 of EM Cases two part podcast on TIA and Stroke with Walter Himmel and David Dushenski – TIA Update – Risk Stratification, Workup and Dual Antiplatelet Therapy.
Much has changed in recent years when it comes to TIA risk stratification, workup and antiplatelet therapy. In this podcast we use the overarching theme of timing to elucidate how to distinguish true TIA from the common TIA mimics, the importance of timing in the workup of TIA, why the duration of therapy with dual antiplatelet therapy and timing of starting anticoagulation in patient with atrial fibrillation, contributes to the difference between preventing catastrophic strokes and causing intracranial hemorrhage. Remember that stroke is a leading cause of adult disability and is the third leading cause of death in Canada. It’s time we paid more attention to TIA…
What follows are excerpts of the podcast show notes:
Clinical Pearl: The “TIA AND” presentation. TIA symptoms AND neck pain – think neck dissection. TIA symptoms AND fever or new heart murmur – think endocarditis.
TIA risk stratification – the death of the ABCD2 scoreThe importance of risk stratification for TIA lies in the questions: what’s the chance that a TIA patient you see in the ED will have a stroke in the next 2 days? 90 days? And can we identify the patients who are eligible for a carotid endarterectomy fast enough to prevent that stroke?
There exists an alarming 12-20% 90 day stroke risk in those presenting with high risk TIA symptoms. Half of these patient suffer from a stroke in the first 48hrs. A 2016 NEJM study fortunately found that this high risk can be reduced to less than 4% with rapid follow-up and aggressive secondary prevention. Based on these findings, it is good practice for high risk TIA patients to be worked up in the first 48 hours.
So which patients who present with TIA symptoms are high risk?
While the CHADS2VASC helps identify AFib patients at risk for future embolic event, The ABCD2 score has been the most ubiquitously used risk stratifying tool in ED since its inception. The elements of the ABCD2 include:
- Age over 60
- Initial BP over 140/90
- Clinical features of unilateral weakness and speech impairment
- Duration of symptoms
- History of D
More recent studies by Stead and Ghia have failed to validate the ABCD2 score and have shown that the score is neither sensitive nor specific and is inaccurate, at any cut-point. In 2011, Perry’s external validation of the ABCD2 found that by using this score, physicians were misclassifying up to 8% of patients as low risk. Sensitivity of the score for high risk patients was found to be only 31.6%.
As recognized in the latest iteration of the Canadian Heart and Stroke Guideline from 2018, the most important prognostic feature of the ABCD2 score appears to be the Clinical features:
While the CHADS2VASC helps identify AFib patients at risk for future embolic event, The ABCD2 score has been the most ubiquitously used risk stratifying tool in ED since its inception. The elements of the ABCD2 include:
- Age over 60
- Initial BP over 140/90
- Clinical features of unilateral weakness and speech impairment
- Duration of symptoms
- History of D
More recent studies by Stead and Ghia have failed to validate the ABCD2 score and have shown that the score is neither sensitive nor specific and is inaccurate, at any cut-point. In 2011, Perry’s external validation of the ABCD2 found that by using this score, physicians were misclassifying up to 8% of patients as low risk. Sensitivity of the score for high risk patients was found to be only 31.6%.
As recognized in the latest iteration of the Canadian Heart and Stroke Guideline from 2018, the most important prognostic feature of the ABCD2 score appears to be the Clinical features:
“Very High Risk for Recurrent Stroke (Symptom onset within last 48 Hours):
- Transient, fluctuating or persistent unilateral weakness (face, arm and/or leg);
- Transient, fluctuating or persistent language/speech disturbance;
- And/or fluctuating or persistent symptoms without motor weakness or language/speech disturbance (e.g. hemibody sensory symptoms, monocular vision loss, hemifield vision loss, +/- other symptoms suggestive of posterior circulation stroke such as binocular diplopia, dysarthria, dysphagia, ataxia).”
The bottom line: high risk patients are the ones with either true motor deficit of a limb or face or a speech deficit. This is important not only to determine who needs a rapid workup to assess eligibility for carotid endarterectomy and hopefully prevent a catastrophic stroke, but also to identify those patients who will likely benefit from dual antiplatelet therapy.
Workup of high risk TIAs – the time to investigate is now, with CTA
CT angiogram of the head and neck improves identification of clinically significant stenosis amenable to endarterectomy compared to carotid doppler ultrasound as well as diagnose both carotid and vertebral artery dissection as a cause for the TIA.
Based on Canadian Stroke Best Practices Guidelines 2018
High risk patients: “Urgent brain imaging (CT or MRI) and non-invasive vascular imaging (CT angiography (CTA) or MR angiography (MRA) from aortic arch to vertex should be completed as soon as possible within 24 hours (Evidence Level B)”
Moderate risk patients*: a) CT/CTA or MRI/MRA (aortic arch to vertex), b) If you don’t have quick access to CTA, an ultrasound of the carotids is an acceptable option.
*Moderate risk = “Fluctuating or persistent symptoms without motor weakness or language/speech disturbance (e.g., hemibody sensory symptoms, monocular vision loss, binocular diplopia, hemifield vision loss, dysarthria, dysphagia, and / or ataxia).”
Which TIA patients need an urgent echocardiogram and/or holter monitor?
Cardio-embolic pathology are a non-trivial source of TIAs and stroke. Five percent of patients with TIA will have atrial fibrillation found on cardiac monitor within 24hrs. 15-20% will have paroxysmal atrial fibrillation on cardiac monitoring within 4 weeks. It is important for these patients to be identified early so that appropriate anticoagulation therapy can be started to prevent further cardio-embolic phenomena.
Those patients being admitted will likely have a full work-up as an inpatient. For patients being considered for outpatient management, which of them requires a holter monitor and echocardiogram to help guide management?
Two groups of TIA patients require urgent echocardiogram and holter monitor:
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.
Dual antiplatelet therapy (DAPT) for TIA – again, timing is everything
Three more recent trials helped demonstrate that the major benefit of DAPT exists early in the course of treatment and the major risks occur later. If DAPT was started appropriately early (usually within 24-72hrs) and not extended beyond 3 weeks, a 1.5-3.5% decreased risk of stroke was found, without significant increased risk of major bleeding.
Our experts therefore recommend immediate loading of DAPT (unless already taking ASA or clopidogrel) for high risk patients and dosing in the following fashion:
Load with ASA 160-325mg chewed followed by ASA 81mg po daily
Load with Clopidogrel 300mg po followed by 75mg po daily for 3 weeks only.
Clinical Pearl: For those patients receiving 3 weeks of dual Prescribe a PPI for gastric mucosal protection, our experts recommend pantoprazole because the other PPI’s affect the cytochrome P450 system and may impair the activation of clopidogrel.
Timing of anticoagulation for patients who you know have atrial fibrillation when they present with a TIA
There’s that timing theme again. If you’re sure it’s a TIA with rull recovery within one hour (no residual symptoms) and a normal CT, consider starting anticogulation (DOAC or warfarin) in the ED. If you’re not sure, consult your neurologist.
I think that I would consider an MRI of the head to rule out an acute but silent stroke before initiating anticoagulation in the above patients.
It is important to understand that for patients with a completed ischemic stroke, with known atrial fibrillation, who are not anticoagulated at the time of their stroke, anticoagulation is not indicated immediately in the ED. Rather, an anticoagulant should be started at a later time during their admission depending on the severity of the stroke.
Disposition for TIA – Which patients should be admitted and which patients can have outpatient management?
We don’t think twice about admitting stroke patients who present outside the thrombolytic window. However, it is high-risk TIA patients that may benefit most from admission for a rapid workup and endarterectomy that may prevent a catastrophic stroke. We can save a high-risk TIA patient from having a massive CVA, but once they’ve stroked out, the benefit of admitting them is far from huge.
Practically, if you can get a CTA in the ED, and it’s negative, outpatient management within 48hrs is reasonable.
If CTA shows carotid stenosis amenable to endarterectomy, admission is advisable. Time is essential – the highest risk time is the first two days and then the first two weeks. Therefore, surgery should be done with 2-14 days after the TIA – the sooner the better. This reduces the risk of a major stroke for 26% over 2 years to 9% – a 17 % absolute risk reduction. The absolute risk reduction is 30% if done within 2 weeks
What follows are some excerpts from the podcast not covered in the show notes [not all are exact quotes]:
Dr. Himmel: 15 to 20% of strokes occurr in persons under 50 with no known risk factors.And the causes are:
- Cervical Artery Dissection
- Patent Foramen Ovale [and other much less common causes of right to left shunt]
- Paroxysmal Atrial Fibrillation
Half of all dissections are non-painful and half of all Patent Foramen ovales are unknown and PFOs are common (20% of all people have a PFO. PFO is diagnosed by an saline contrast echocardiogram.*)
*See References 3 through 6 below for information on the saline contrast echocardiogram and the diagnosis of right to left shunt as a cause of cryptogenic stroke.
27:00 The workup of a high risk or moderate risk TIA requires an expedited (meaning right away) non-contrast CT of the brain to look for bleeds and a CT angiogram to look at the arteries from extracranial to intracranial arteries right to the vertex.
31:30 5% of TIA patients in normal sinus rythm if monitored for 24 hours will be found to have paroxysmal atrial fibrillation. If monitored for four weeks 15-20% will be found to have paroxysmal atrial fibrillation.
32:00 There are only three treatments of TIA to prevent stroke.
- Dual Platelet Therapy
- Anticoagulation
- Surgery [Carotid Endarterectomy]
What about anticoagulation for TIA or Stroke?
The Canadian Guidelines on atrial fibrillation, Resource (9) below, recommend using CHADS 65 to risk stratify and treat pts with AF.
Additional Resources
(1) Ep 117 TIA Update – Risk Stratification, Workup and Dual Antiplatelet Therapy November, 2018 from Emergency Medicine Cases.
(2) After The Diagnosis Of TIA – Determining The Urgency Of The Workup
Posted on August 21, 2017 by Tom Wade MD
(3) Saline Shunt Study for the Evaluation of an ASD or PFO from EchocardiograpahySkills.Com – Imaging Skills For Echocardiography: A detailed guide for students, sonographers and physicians [Accessed 11-23-2018]
(4) Saline Contrast Echocardiography in the Era of Multimodality Imaging–Importance of “Bubbling It Right” [PubMed Abstract] [Full Text HTML] [Full Text PDF]. Echocardiography. 2015 Nov;32(11):1707-19. doi: 10.1111/echo.13035. Epub 2015 Aug 7.
(5) An Unusual Cause of Stroke—the Importance of Saline Contrast Echocardiography [PubMed Abstract]. Echocardiography. 2008 Sep;25(8):908-10. doi: 10.1111/j.1540-8175.2008.00706.x.
Abstract
We report a case of a 38-year-old man who presented with a cryptogenic stroke in whom a persistent left superior vena cava (PLSVC) to the left atrium was established as an isolated anomaly by both echocardiography and magnetic resonance angiography. This rare cardiac abnormality creates a systemic right to left shunt and the potential for cerebral abscess or infarction. Echocardiographic diagnosis may be missed unless intravenous saline contrast is performed using a left upper extremity vein.
(6) Evaluating the potential risks of bubble studies during echocardiography [PubMed Abstract]. Perfusion. 2015 Apr;30(3):219-23. doi: 10.1177/0267659114539182. Epub 2014 Jun 19.
(8) Canadian Stroke Best Practice Recommendations for Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care, 6th Edition, Update 2018 [PubMed Abstract] [Full Text HTML] [Full Text PDF].
(9) 2016 Focused Update of the Canadian Cardiovascular Society Guidelines for the Management of Atrial Fibrillation [PubMed Abstract] [Full Text HTML] [Full Text PDF]
