Evaluation and
Management of Syncope
Syncope
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Definition:
Sudden transient loss of consciousness
and postural tone with subsequent
spontaneous recovery. ( Greek synkope,
“cessation, pause”).
Transient inadequate cerebral perfusion.
Syncope - Epidemiology
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1% of hospital admissions
3% of ER visits
6% annual incidence in the elderly
Upto 50% of young adults have history of
isolated LOC
Annual cost $2 B (2005)
Clin Electrophysiol 22:1386,1999
Sun BC, Am J Cardiol 95:668, 2005
Syncope - Prognosis
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Highest mortality in patients with cardiac cause
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Neurally mediated syncope/ medication induced
syncope did not increase mortality
Soteriades ES, et al: N Eng J Med 347:878, 2002
Causes of Syncope
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Vascular ( 58 – 62 % ) : Reflex mediated,
orthostatic, anatomic
Cardiac ( 10 – 23 % ): Arrhythmias, anatomic
Neurologic/cerebrovascular* ( 0.5 – 5 % )
Metabolic/drugs ( 0 – 2 % )
Psychogenic* ( 0.2 – 1.5 % )
Syncope of unknown origin ( 14 – 18 % )
Sarasin FP, Am J Med 111: 177, 2001
Alboni P, JACC 37, 1921, 2001
Differential Diagnosis of Syncope
Obstruction to Flow
Aortic Stenosis
Hypertrophic
Cardiomyopathy
Atrial Myxoma
Mitral Stenosis
Pulmonic Stenosis
Pulmonary Hypertension
Pulmonary Embolism
Cardiac Tamponade
Aortic Dissection
Bradyarrhythmias
Sinus Node Dysfunction
AV Block
Pacemaker Malfunction
Tachyarhythmias
Ventricular Tachycardia
Torsade de Pointes
Supraventricular
Tachycardia
Other Causes of
Syncope
Vasovagal Syncope
Carotid Sinus
Hypersensitivity
Drug-Induced
Orthostatic Hypotension
Cerbrovascular Disease
Situational (e.g.
cough/micturition syncope)
Hypoglycemia
Seizure
Psychogenic
Syncope - Clinical Features Suggestive of
Specific Causes
Symptom or Finding
Diagnostic Consideration
After sudden unexpected pain,
unpleasant sight, sound or smell
Vasovagal syncope
During/immediately after
micturition, cough, swallow or
defecation
On standing
Situational syncope
Prolonged standing
Vasovagal syncope
Orthostatic hypotension
Syncope – Clinical Features Suggestive of
Specific Causes (cont’d )
Symptom or Finding
Diagnostic Consideration
Well-trained athlete after exertion Neurally mediated
Change in position ( from sitting Atrial myxoma, thrombus
to lying, bending, turning over in
bed )
Syncope during exertion
Aortic stenosis, pulmonary
hypertension, pulmonary
embolus, mitral stenosis, IHSS,
CAD, neurally mediated syncope
Syncope – Clinical Features Suggestive of
Specific Causes ( cont’d )
Symptom or Finding
Diagnostic Consideration
With head rotation, pressure on cartoid Cartoid sinus syncope
sinus (as in tumors, shaving, tight
collars)
Associated with vertigo, dysarthria,
diplopia, and other motor and sensory
symptoms of brain stem ischemia
Transient ischemic attack, subclavian
steal, basilar artery migraine
With arm exercise
Subclavian steal
Confusion after episode
Seizure
Seizure vs Syncope
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Seizure:
Aura, frothing at the mouth
Horizontal eye deviation, tongue biting
Elevated BP, sinus tach
Sustained tonic clonic movements, incontinence
Disorientation, slow recovery
Syncope – Diagnostic Tests
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History and physical examination: cardiac disease,
family h/o SCD, medications, witness
Orthostatic BP check
ECG: Q waves, QTc, delta wave, epsilon wave
Holter monitor: V pause > 3 sec while awake, Mobitz
type 2 or CHB, VT.
Arrhythmia event monitor
Echocardiogram
Tilt table test
Electophysiologic testing
Diagnostic Tests for Syncope
Test
Indication
Disadvantage
Holter Monitor
Frequent symptoms of
palpitations or dizziness
Low yield if symptoms
are intermittent
Continuous-Loop
Recorder
Intermittent or very
transient symptoms;
patient has little warning
before symptoms occur
Inconvenient to use for
long periods of time
Implantable Loop
Recorder
Infrequent episodes of
syncope; diagnosis
cannot be made
noninvasively
Requires invasive
procedure
Signal-Averaged ECG
Syncope and structural
heart disease
Low positive predictive
value
Diagnostic Tests for Syncope
(cont’d)
Test
Indication
Disadvantage
Upright Tilt Testing
Suspected vasovagal
Inadequate
syncope; syncope without reproducibility
structural heart disease
Electrophysiologic Study
Syncope when diagnosis
cannot be made noninvasively; syncope with
structural heart disease
Invasive; low yield when
no structural heart
disease
Syncope – Indications For Hospitalization
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Presence of heart disease, dyspnea, CHF,
VT, acute coronary syndrome
ECG suggestive of arrhythmic syncope in:
WPW, long QTc, Sick Sinus Syndrome, AV block, VT,
Brugada syndrome, RV dysplasia
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Syncope with severe injury
Syncope during exercise
Family h/o sudden cardiac death
Sinus Arrest on Holter Monitor
ACCSAP 2005
Syncope – Loop Event Recorder
ACCSAP 6, 2005
Implantable Loop Recorder
Implanted Loop Event Recorder
Head Up Tilt Table Testing
Tilt Table Testing: When to do it?
For diagnosis:
 Suspected
reflex, atypical presentation
 Unexplained syncope at the end of work-up,
orthostatic trigger present
 Suspected delayed orthostatic hypotension
Neurally Mediated Syncope
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Also known as vasovagal syncope.
Recurrent syncope in the absence of structural
heart disease is most likely neurally mediated.
Head-upright tilt test maximizes venous pooling,
sympathetic activation and circulating
catecholamines.
Most vasovagal episodes involve both
cardioinhibition (drop in heart rate) and
vasodepressor response (drop in BP).
Case # 1
A 20 year old female presents with recurrent near
syncope and syncope preceded by nausea, sweating
and gradual “tunnel vision”usually after prolonged
standing. The ECG and 2-D echocardiogram are
normal. What would be the next step?
Answer: Tilt table test.
Q: What is the mechanism for the visual symptoms?
Answer: Collapse of peripheral vessels of the retina.
Syncope:
The Role of Electrophysiologic Testing
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Most important diagnostic tool is the history
High risk historical elements
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Syncope resulting in injury
Syncope resulting in motor vehicle accident
Syncope in the setting of structural heart disease
 Syncope preceded by palpitations
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Syncope while supine
Abnormal ECG
Lack of “low risk” elements
Guidelines for EP Testing in
Syncope
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Class I: General agreement
Patients with structural heart disease and unexplained
syncope
Class II: Less certain, but accepted
Patients with recurrent unexplained syncope without
structural heart disease and a negative tilt test
Class III: Not indicated
Patients with known cause of syncope in whom
treatment will not be guided by EP testing
Electrophysiologic Testing in
Syncope
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Sinus node function: prolonged sinus node
recovery time
Abnormal AV conduction: ↑HV interval, infra
His block
Inducibility of sustained VT
Inducibility of rapid SVT with symptoms,
hypotension
Neurally Mediated Syncope
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Precipitating factors: prolonged standing,
dehydration, alcohol, diuretics, vasodilators.
Sit/lie down at onset of symptoms, cross the legs
and tense them together if sitting.
Salt supplementation and fluids.
Isometric arm, leg counterpressure.
Moderate aerobic and isometric exercise.
Tilt training.
Therapy of Neurocardiogenic Syncope
Treatment
Mechanism
Volume expansion (increase salt and
fluid intake, fludrocortisone)
Maintain ventricular volume
Beta-Blockers
Block response to adrenergic stimulation; reduce
ventricular contractility; prevent activation of
ventricular mechanoreceptors
Anticholinergic agents (scopolamine,
disopyramide)
Block vagal response; reduce ventricular
contractility (disopyramide)
Serotonin reuptake inhibitors
Prevent vasodilation and bradycardia possibly by
downregulation of response to serotonin
Methylxanthines
Adenosine receptor antagonist;
Phophodiesterase and Ca++ transport inhibitor
(maintain vascular tone)
Midodrine
Adrenergic agonist
Cardiac pacing
Maintain heart rate, AV synchrony
Pharmacologic Therapy of Neurally
Mediated Syncope
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Despite the widespread use of drug therapy,
none of these pharmacologic agents have been
demonstrated to be effective in large prospective
randomized clinical trials.
A small study has reported the efficacy of
midodrine.
Metoprolol, propranolol and nadolol are no more
effective than placebo.
Orthostatic Intolerance Syndrome
Vasovagal Syncope
Counterpressure
Maneuvers
JACC 2006 48:1652
Delayed Orthostatic
Intolerance
Elastic Stockings
JACC 2006: 48:1425
Syncope - Prognosis
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Highest mortality in patients with cardiac cause

Neurally mediated syncope/ medication induced
syncope did not increase mortality
Soteriades ES, et al: N Eng J Med 347:878, 2002
Suggested Strategies for
Syncope Management
Syncope:
May be a harbinger of sudden cardiac death
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Evaluation – purpose is to determine if pt is at
increased risk for death
Identify pts with underlying heart disease
(ischemic CM, non-ischemic CM, HCM),
myocardial ischemia, WPW, genetic diseases
(long-QT syndrome, Brugada Syndrome),
catecholaminergic polymorphic VT
Case # 2
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65 year old male with h/o inferior wall myocardial
infarction 1 year ago presents with rapid palpitation
and syncope. An ECG shows SR and old inferior
wall myocardial infarction. A 2D echo shows LVEF
40% with inferoapical dyskinesis. Coronary
angiography reveals totally occluded right coronary
artery with collaterals. What is the next step?
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Answer: Electrophysiologic study (to look for
inducible sustained VT)
Case #3
72 year old male with chronic atrial fibrillation of
greater than 10 years’ duration is admitted following
a syncopal episode. A 2D echo shows markedly
dilated left atrium and LVEF 60%. Telemetry
reveals atrial fibrillation with slow ventricular
response and pauses of 5 to 7 seconds associated
with near syncope.
How would you proceed?
Answer: Implant single chamber rate
responsive pacemaker
Diagnostic Evaluation of Syncope
Syncope
Hx, physical exam, supine and upright
BP, EKG
Unexplained syncope
Is there structural heart disease?
NO
YES
Tilt table test
Electrophysiologic
Study