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Sudden Cardiac Death

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					Syncope, Sudden Cardiac Death and Devices


           Dr. Prapa Kanagaratnam
               Imperial College
                                        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
                                                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. 2002;347(12):878-885. [Framingham Study Population]
                            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
                                               Syncope Mimics

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



Brignole M, et al. Europace, 2004;6:467-537.
                       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
                           Bradycardia

   Symptoms:
        Syncope/Presyncope
        Lethargy/reduced exercise tolerance
        Heart failure


   Exclude ischaemia

   Exclude reversible causes
         Drugs – betablockers, digoxin, verapamil, amiodarone
         Hypothyroidism
         Electrolyte imbalance
   Bradycardia


  Sinus bradycardia




Sick sinus syndrome




   Sinus pauses




  Complete HB
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
               Definition

 An unexpected death from a cardiac cause
occurring within 1 hour of onset of symptoms.
                    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 <5%.
               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
                    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.
    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)
                  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
Ischaemic scar related VT




                            Exit site
               Entry
               Site
          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.
      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
                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
Normal ECG




Brugada Syndrome
        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 >460ms in women/children <15yrs, >450ms in men

   Up to 30% gene carriers have normal QTc.
     Arrhythmogenic Right Ventricular Dysplasia

   Regional or global fibro-fatty replacement of myocardium.

   1:1000 to 1:10 000 incidence.

   Familial in 30% with autosomal dominant with incomplete
    penetrance.

   Syncope, sustained VT and cardiac arrest.
ARVD - Gross and microscopic structural abnormalities
Implantable Defibrillator



                              Monitoring




                              Detection

                  Biphasic shock
                  RVcoil/SVC coil/Active Can
Implantable Cardioverter Defibrillator
        Secondary Prevention with ICDs
Study      Pts    Criterion       Ejection Risk
                                  fraction reduction
                                  (%)      (%)

AVID       1016 Cardiac arrest,   32       31          P<0.02
                sustained VT
CIDS       659 Cardac arrest,     34       20          P=0.14
                sustained VT
CASH       288 Cardiac arrest     45       23          P=0.08

META-      1866                   34       28          P=0.006
ANALYSIS
            Primary Prevention with ICDs
Study       Pts    Criterion         Ejection   Risk
                                     fraction   reduction
                                     (%)        (%)
MADIT       196    IHD, EF<35%,     26          54            P=0.009
                   nonsustained VT,
                   VT on EPS
CABGpatch   900    EF <36%,          27         7% increase
                   Abnormal signal
                   averaged ECG
MUSTT       704    IHD, EF <40%,     30         51            P<0.001
                   Non-sustained
                   VT, VT on EPS
MADIT II    1232   MI, EF<30%        23         31            P=0.016

SCD-Heft    2521   EF<35%            25         23            P=0.007
                   NYHA II/III
        NICE guidelines on ICDs (2006)
   Primary prevention for patients with history of previous
    infarction (>4 weeks) with

    Either all of the following :
                  Non-sustained VT on 24hr ECG
                  Inducible VT on EP testing
                  LV dysfunction EF<35% (<NYHA III)

     or all of the following:
                 EF <30%(<NYHA III)
                 QRS>120ms
             Primary prevention cont’d

   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.
               NICE guidelines cont’d
   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 < NYHA III
         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.
Baseline Unpaced   Synchronised pacing
Impact of Cardiac Resynchronization Therapy in HF Total
     Days Hospitalized Through 6 M in MIRACLE

    All-Cause Hospitalization*   Heart Failure Hospitalization#
               62%                             81%
            P=0.002                        P=0.035




               Control (N=189)   CRT (N=181)
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.
                          Summary
   Definition of SCD

   Epidemiology/Aetiologies

   Risk factors

   Investigative tools

   ICD trials and NICE guidelines

   Few conditions associated with SCD.

				
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posted:7/29/2011
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