Syncope, Sudden Cardiac Death and Devices

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Syncope, Sudden Cardiac Death and Devices

• Dr. Prapa Kanagaratnam
• Imperial College

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What Is Syncope?

• Syncope
• A sudden temporary loss of consciousness
  associated with loss of postural tone
• Due to abrupt reduction or loss of cerebral
  perfusion1

1 Grubb, Olshansky (eds). Syncope Mechanisms and
Management. Armonk, NY Futura Publishing Co.,
Inc., 1998, p.1
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Syncope Mortality

• Low mortality vs. high mortality
• Vasovagal syncope vs. syncope with a cardiac
  cause

Soteriades ES, Evans JC, Larson MG, et al.
Incidence and prognosis of syncope. N Engl J
Med. 2002347(12)878-885. Framingham Study
Population
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A Diagnostic Plan

• Initial Examination
• Detailed patient history / Physical exam
• Supine and upright blood pressure
• Monitoring
• ECG
• Holter /Event
• Insertable Loop Recorder (ILR)
• Echo
• Special Investigations
• Tilt test
• Electrophysiology study

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Syncope Mimics

• Acute intoxication (e.g., alcohol)
• Seizures
• Sleep disorders
• Somatization disorder (psychogenic
  pseudo-syncope)
• Trauma/concussion
• Hypoglycemia
• Hyperventilation

Brignole M, et al. Europace, 20046467-537.
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A Diagnostic Plan

• Initial Examination
• Detailed patient history / Physical exam
• Supine and upright blood pressure
• Monitoring
• ECG
• Holter /Event
• Implantable Loop Recorder (ILR)
• Echo
• Special Investigations
• Tilt test
• Electrophysiology study

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Bradycardia

• Symptoms
• Syncope/Presyncope
• Lethargy/reduced exercise tolerance
• Heart failure
• Exclude ischaemia
• Exclude reversible causes
• Drugs betablockers, digoxin, verapamil,
  amiodarone
• Hypothyroidism
• Electrolyte imbalance

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Bradycardia
Sinus bradycardia
Sick sinus syndrome
Sinus pauses
Complete HB
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Sudden Cardiac Death

• Cameroon international footballer Marc Vivien
  Foe died after collapsing on the pitch while
  playing for his country in the Confederations Cup
  semi-final against Colombia. June 27 2003

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Definition

• An unexpected death from a cardiac cause
  occurring within 1 hour of onset of symptoms.

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Epidemiology

• SCD incidence 50,000 to 70,000 per annum in the
  UK.
• 80-90 are due to ventricular arrhythmias.
• 85-90 are due to 1st event, 10-15 due to
  recurrent events.
• Survival rates for out of hospital arrest lt5.

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Cardiac Aetiologies of SCD

• Coronary artery disease (80)
• Cardiomyopathies - DCM, HOCM, ARVD.
• Channelopathies -Long/Short QT Sydrome,
• -Brugada Syndrome.
• Other -Valvular heart disease
• -Wolf-Parkinson White

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Risk factors for SCD

• Previous cardiac arrest.
• Previous myocardial infarction/coronary artery
  disease.
• Previous history of ventricular arrhythmias.
• Poor LV function i.e. heart failure.
• Family history SCD, HOCM, Long QT, etc.

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Investigative Tools for sudden cardiac death risk

• ECG - Myocardial infarction
• Brugada Sydrome
• Long QT
• Wolf-Parkinson White Syndrome
• ECHO - LV function
• Cardiomyopathy (DCM/HCM)
• Valves (AS)

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Other Specialist Tests

• Angiography -Coronary artery disease
• MRI -Arrhythmogenic RV dysplasia
• -Hypertrophic Cardiomyopathy
• EP study -risk stratification,
• -ICD programming
• -exclude other arrhythmias
• Genetic testing -Long QT/HCM/Brugada

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Ischaemic scar related VT
Exit site
Entry Site
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Dilated Cardiomyopathy (DCM)

• Global, usually idiopathic myocardial disorder -
  enlargement and inadequate function of the left
  ventricle.
• Idiopathic DCM 40 familial.
• 5yr mortality 20, SCD 8-51 of death.
• Presentation palpitations, (pre)syncope, arrest.

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Hypertrophic Obstructive Cardiomyopathy

• Inherited autosomal dominant.
• 1 of every 500 adults
• Usually asymmetric thickening of LV wall
• Presentation SOB, chest pain, palpitations,
  pre/syncope, cardiac arrest.
• Diagnosis - abnormal ECG 90 ECHO

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The Brugada Syndrome

• Channelopathy mutations in sodium channel gene
• Autosomal dominant inheritance with incomplete
  penetrance
• 5 to 66 per 10 000 with male predominance
• ST segment elevation in precordial leads
  associated with polymorphic VT/SCD
• Presentation with arrest, syncope, family
  history, nocturnal agonal breathing

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Normal ECG
Brugada Syndrome
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Congenital Long QT syndrome (LQTS)

• Inherited mutations of cardiac ion channel
  protein genes.
• Stress-mediated ventricular arrhythmias causing
  syncope and cardiac arrest.
• Diagnosis dependent on ECG, presentation and
  family history.
• QTc gt460ms in women/children lt15yrs, gt450ms in
  men
• Up to 30 gene carriers have normal QTc.

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Arrhythmogenic Right Ventricular Dysplasia

• Regional or global fibro-fatty replacement of
  myocardium.
• 11000 to 110 000 incidence.
• Familial in 30 with autosomal dominant with
  incomplete penetrance.
• Syncope, sustained VT and cardiac arrest.

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ARVD - Gross and microscopic structural
abnormalities
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Implantable Defibrillator
Monitoring
Detection
Biphasic shock RVcoil/SVC coil/Active Can
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Implantable Cardioverter Defibrillator
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Secondary Prevention with ICDs
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Primary Prevention with ICDs
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NICE guidelines on ICDs (2006)

• Primary prevention for patients with history of
  previous infarction (gt4 weeks) with
• Either all of the following
• Non-sustained VT on 24hr ECG
• Inducible VT on EP testing
• LV dysfunction EFlt35 (ltNYHA III)
• or all of the following
• EF lt30(ltNYHA III)
• QRSgt120ms

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Primary prevention contd

• A familial cardiac condition with a high risk of
  sudden death
• Long QT, HOCM, Brugada, ARVD or has undergone
  surgical repair of congenital heart disease.

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NICE guidelines contd

• Secondary prevention for the following
• (in the absence of treatable causes) 
• Cardiac arrest due to either VT or VF
• Spontaneous sustained VT causing syncope or
  significant haemodynamic compromise
• Sustained VT without syncope/cardiac arrest, and
  who have an associated reduction in ejection
  fraction (less than 35) but lt NYHA III

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Biventricular Pacemaker/Defibrillator (CRT)

• In some patients dysynchronous contraction
  contributes to poor left ventricular function
• Usually due to left bundle branch block
• the dysynchronous element may be overcome by
• cardiac resynchronisation therapy
• This involves pacing both ventricles even though
  a cardiac pacemaker is not required for rhythm
  problems.

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Baseline Unpaced
Synchronised pacing
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Impact of Cardiac Resynchronization Therapy in HF
Total Days Hospitalized Through 6 M in MIRACLE
All-Cause Hospitalization
Heart Failure Hospitalization
? 62
? 81
P0.002
P0.035
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Wolf-Parkinson White Syndrome

• Accessory pathway between atria and ventricles.
• 1.5 per 1000 population
• Short PR, broad QRS with delta wave
• Sudden cardiac death related to rapidly conducted
  atrial fibrillation over pathway leading to VF.

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Summary

• Definition of SCD
• Epidemiology/Aetiologies
• Risk factors
• Investigative tools
• ICD trials and NICE guidelines
• Few conditions associated with SCD.