Transient Ischemic Attack (TIA): The Calm Before the Storm

Raymond Reichwein, M.D.

Associate Professor of Neurology

Penn State University College of Medicine

Milton S. Hershey Medical Center

January 8, 2009

Disclosures

• Boehringer Ingelheim

• Genentech

• AGA Medical Corp

OBJECTIVES

• Discuss the importance of TIA and future stroke risk.

• Discuss optimal TIA evaluation and management.

• Briefly discuss future stroke prevention, from both an antiplatelet/anticoagulant therapy and risk factor management standpoint.

04/11/23

1. Broderick J et al. Stroke. 1998;29:415-421.2. American Heart Association. 2002 Heart and Stroke Statistical Update. 2001.3. Pulsinelli WA. Cerebrovascular diseases. Cecil Textbook of Medicine. 1996.

Stroke in the US

• 730,000 new or recurrent strokes each year1

• 167,366 deaths in 1999 (1 of every 14.3 deaths)2

• 4,600,000 stroke survivors alive today2

• Origin of strokes3

– 80% ischemic

– 20% hemorrhagic

TIA

• Underrecognized

• Underreported

• Undertreated

TIA Knowledge

• Among 10,112 participants– 8.2% correctly related the definition of TIA– 8.6% could identify a typical symptom– Men, non-whites, and those with lower income

and fewer years of education were less likely to be knowledgeable about TIA.

Johnston, et al, Neurology 2003

TIA Definition

• Resolution of acute neurological/stroke deficits within 24 hours.

• No imagable acute ischemic stroke changes.

TIAs

• The majority of TIAs resolve within 60 minutes, and most resolve within 30 minutes.

• Less than 15% chance of complete resolution of symptoms if last >1 hour (Levy).

• NINDS IV t-PA trial data revealed only 2% chance of complete symptom resolution @ 24 hours, for neurological symptoms/deficits that didn’t completely resolve within 1 hour or rapidly improve within 3 hours.

TIA Epidemiology• >200,000 events per year (compared to >730,000

strokes per year).• Approximately 10-20% of patients will experience a

stroke after a TIA within the first 90 days, and in approx. 50% of these patients, the stroke occurs in the first 24-48 hours.

• Factors associated with increased stroke risk: advanced age, diabetes mellitus, symptoms more than 10 minutes, weakness, and impaired speech. Large artery atherothrombotic disease more likely to present with a TIA before a stroke, versus other etiologies.

TIA Epidemiology

• Several recent studies reveal a >10% stroke risk in the 90 days after a TIA.

• The risk of stroke within the first 48 hours after TIA is approximately 5% (greater than MI risk after presenting with acute chest pain syndrome).

• Blacks and men had higher stroke risk.

Event Risk Within 3 MonthsEvent Risk Within 3 MonthsAfter TIAAfter TIA

Johnston SC, et al. JAMA. 2000;284:2901 2906.

RecurrentTIA

Cardiac Event

Stroke Death

Ev

ent

Ra

te

12.7%

2.6% 2.6%

10.5%

5% in

48 h

• age > 60 years

• diabetes mellitus

• duration of episode greater than 10 min

• weakness and speech impairment with the episode

Independent risk factors for stroke within 90 days

after TIA:

TIA before Stroke by Subtype

• Large-artery atherothrombotic disease: 25-50%.

• Cardioembolic sources: 10-30%.

• Small vessel/lacunar disease: 10-15%.

Symptomatic Internal Carotid Artery Disease

• NASCET Medical Arm Data (600 patients)• Two-day risk was 5.5%. • 90-day ipsilateral stroke risk was 20%. • Degree of stenosis (>70% stenosis) didn’t confer

increased stroke risk. • Infarct on brain imaging and presence of

intracranial major-artery disease doubled the early stroke risk.

• Benefit from CEA declines rapidly over several weeks, particularly in women (Oxford data).

Cumulative Risk of Stroke

Post-TIA (%)

4 – 8

12 – 13

24 – 29

30 days

1 year

5 years

Post-Stroke (%)

3 – 10

5 – 14

25 – 40

Sacco. Neurology. 1997;49(suppl 4):S39.Feinberg et al. Stroke. 1994;25:1320.

TIA and ischemic stroke pathophysiology are the same.The only difference is transient versus persistent neurological

deficits. Certainly, a TIA state is a much better clinical state to intervene and prevent a future

disabling stroke.

Risk Factors for First Ischemic Risk Factors for First Ischemic StrokeStroke

Adapted from Sacco RL. Neurology 1998;51(suppl 3):S27-S30.

Hypertension Atrial fibrillation Cigarette smoking Hypercholesterolemia Heavy alcohol use Asymptomatic carotid

stenosis Transient ischemic

attack

Nonmodifiable Modifiable (value established)

Age Gender Race/Ethnic Heredity

Stroke in Young Individuals

• Clotting disorders

• Migraine

• Birth control pills

• Illicit drug use

• Arterial dissection

• Patent foramen ovale

• Autoimmune disorders (lupus)

TIA Evaluation

• Prompt evaluation and intervention is the key.

• Most TIA patients should be admitted for diagnostic evaluation and management (Observation unit or equivalent); often significant delay if done as outpatient.

• TIA and ischemic stroke diagnostic evaluations should be the same.

Who should be admitted??

• Anyone with no prior/recent TIA/stroke diagnostic workup; new suspected etiology despite prior workup.

• Suspected large vessel (anterior or posterior circulation) events.

• Most suspected lacunar/small vessel events, particularly if no prior workup (? calm before the storm).

• Recurrent/crescendo TIAs.

ABCD2 Score

• Age 60 or older 1 point• Blood pressure >140/90 1 point• Clinical

- Unilateral weakness 2 points- Speech impairment 1 point

• Duration- 60 minutes or more 2 points- Less than 60 minutes 1 point

• Diabetes 1 point

ABCD2 Score

• Score 4 or greater – admit to hospital (moderate-high stroke risk).

• Score predicted risk similarly among all ethnic backgrounds.

• Best predictor of 2, 7, and 90 day stroke risk among validated scales.

Inpatient TIA Management• Neurochecks; follow blood pressures.• ? Cardiac telemetry (paroxysmal a. fib).• ? Intravenous Heparin for suspected high risk TIA

sources, pending completion of diagnostic evaluation.• Diagnostic evaluation should be completed within 24

hours; make decision regarding admission or discharge at that point.

• Potential IV t-PA use for recurrent event (acute ischemic stroke) while hospitalized.

Presumptive TIA/stroke etiology determines optimal treatment, as well as risk for recurrent events.

Stroke Subtypes and Incidence

Albers et al. Chest 2004; 126 (3 Suppl): 438S–512S.

Ischaemic stroke85%

Hemorrhagic stroke15%Other

5%

Cryptogenic30%

Cardiogenicembolism

20%

Small vesseldisease

“lacunes”25%

Atheroscleroticcerebrovascular

disease20%

TIA BRAIN IMAGING

• Prior CT(brain) studies revealed a 15-20% incidence of cerebral infarction in a vascular territory related to the patient’s symptoms/deficits.

• Newer MRI(brain) studies, using diffusion-weighted imaging (DWI), reveal approx. 30-50% acute ischemic stroke findings, and about half of these persisted on follow-up imaging. Best correlated with prolonged TIA symptoms.

MRI Diffusion Imaging

• Distinguish new versus old ischemic areas.

• Distinguish new ischemic areas even with clinical TIA.

• Differentiate stroke etiology (small vessel vs. large vessel; embolic sources).

Acute Embolic Strokes

Acute Ischemic Stroke