Title: Sudden Cardiac Death
1Sudden Cardiac Death
- Suhail Allaqaband, MD
- University of Wisconsin-Milwaukee Clinical Campus
- Sinai Samaritan Medical center
2- Sudden cardiac death (SCD) is a syndrome defined
by its clinical presentation rather than by a
discrete pathophysiology - The World Health Organization definition has been
widely accepted sudden collapse occurring within
one hour of symptoms - However, as the name implies, SCD is
instantaneous and most individuals become
unconscious within seconds to minutes as a result
of insufficient cerebral blood - Underlying heart disease is present the vast
majority of patients with SCD
3Sudden Cardiac Death
- Incidence
- 400,000 - 500,000/year in U.S.
- Only 2 - 15 reach the hospital
- Half of these die before discharge
- High recurrence rate
4Underlying Arrhythmia of Sudden Death
Primary VF 8
Torsades de Pointes 13
VT 62
Bradycardia 17
5ARRHYTHMIC MECHANISM OF SUDDEN CARDIAC DEATH
- In approximately 80 percent of cases, a sustained
ventricular arrhythmia is preceded by an increase
in ventricular ectopy - These spontaneous arrhythmias are present for a
variable period of time prior to the development
of a sustained ventricular tachyarrhythmia - In about one-third of cases, the tachyarrhythmia
is initiated by an early R on T ventricular
premature beat in the remaining two-thirds, the
arrhythmia is initiated by a late cycle VPB
6ARRHYTHMIC MECHANISM OF SUDDEN CARDIAC DEATH
- A bradyarrhythmia or asystole is an important but
less common cause of SCD, being observed in only
about 10 percent of cases - A bradyarrhythmia is more often associated with a
nonischemic cardiomyopathy
7ETIOLOGY OF SUDDEN CARDIAC DEATH
- There are many cardiac and noncardiac causes for
a sustained ventricular tachyarrhythmia that can
result in SCD - In one study of 809 patients with a cardiac
arrest, 34 percent had a noncardiac origin, most
commonly due to trauma, nontraumatic bleeding,
intoxication, near drowning, or pulmonary
embolism
8Causes of Sudden Cardiac Death
- Nonischemic Heart Disease (cont)
- myocarditis
- acute pericardial tamponade
- acute myocardial rupture
- Noncardiac Disease
- sudden infant death syndrome
- drowning
- Pickwickian syndrome
- pulmonary embolism
- drug-induced
- airway obstruction
- no structural heart disease - primary electrical
disease, chest wall trauma (commotio cordis),
Brugadas syndrome (right bundle branch block
and ST segment elevation V1 to V3)
- Ischemic Heart Disease
- CAD with MI or angina
- coronary artery embolism
- nonathogenic coronary artery disease
- coronary artery spasm
- Nonischemic heart disease
- CAD without MI or angina
- cardiomyopathy - obstructive, nonobstructive,
nonischemic - valvular heart disease
- congenital heart disease
- prolonged QT syndrome
- preexcitation syndrome
- complete heart block
- arrhythmogenic RV dysplasia
9ETIOLOGY OF SUDDEN CARDIAC DEATH
- Most patients who experience SCD have an
underlying cardiac abnormality, particularly
coronary heart disease - The incidence of SCD increases with age in both
men and women - However, at any level of multivariate risk, women
are less vulnerable to sudden death than men and
a higher fraction of SCDs in women occur in the
absence of prior overt coronary heart disease
10Incidence of Sudden Death Increases with Age
During a 38 years follow-up of subjects in the
Framingham Heart Study, the annual incidence of
sudden death increased with age in both men and
women.However, at each age, the incidence of
sudden death is higher in men than women. (Am
Heart J 1998 136205)
11ETIOLOGY OF SUDDEN CARDIAC DEATH
- Symptoms of an acute ischemic episode are
generally absent, and the collapse is typically
instantaneous, without any warning - Approximately 75 to 80 percent of patients have
no ECG changes or enzyme abnormalities after
resuscitation that are suggestive of an acute
myocardial infarction as a precipitating factor -
12Clinical Substrates Associated with VF Arrest
- Myocardial ischemia and infarction
- Acute myocardial infarction is associated with an
approximate 15 risk of VF within the first 24 to
48 hours, with the incidence falling to only 3
percent over the next several days - When VF is provoked by an AMI, symptoms of the
infarction are present for minutes to hours
before sudden death occurs over 80 percent of VF
episodes occur within the first 6 hours
13Clinical Substrates Associated with VF Arrest
- Congestive heart failure
- The presence of CHF increases overall mortality
and the incidence of SCD in both men and women
14CHF Predict Increased Sudden Death and Overall
Mortality
During a 38 years follow-up of subjects in the
Framingham Heart Study, the presence of CHF
significantly increased sudden death and overall
mortality in both men and women. P lt0.001.
15Risk of Sudden Death Data from GISSI-2 Trial
1.00
1.00
0.98
0.98
p log-rank 0.002
0.96
0.96
0.94
0.94
Survival
Survival
0.92
0.92
p log-rank 0.0001
0.90
0.90
0.88
0.88
A
B
0.86
0.86
0
30
60
90
120
150
180
0
30
60
90
120
150
180
Days
Days
- Patients withoutLV Dysfunction
Patients withLV Dysfunction
No PVBs1-10 PVBs/hgt 10 PVBs/h
16Clinical Substrates Associated with VF Arrest
- Left ventricular hypertrophy
- Hypertension with LVH appears to increase the
risk of SCD - In one study, patients with hypertension and LVH
who died suddenly had less extensive coronary
disease than normotensives who had SCD - These findings suggest that the hypertrophied
myocardium is more susceptible than normal
myocardium to the the effects of ischemia
17Clinical Substrates Associated with VF Arrest
- Absence of structural heart disease (primary
electrical disease) - Rarely, SCD occurs in patients younger than 40
years of age who have no evidence of structural
heart disease - However, in approximately 90 percent of these
cases autopsy reveals evidence of underlying
heart disease that was unrecognized, including
myocarditis, hypertrophic cardiomyopathy,
arrhythmogenic RV dysplasia, sarcoidosis, or
asymptomatic coronary heart disease - The remaining 10 percent of patients have
idiopathic ventricular fibrillation ("primary
electrical disease)
18Clinical Substrates Associated with VF Arrest
- Brugada's syndrome
- One interesting subgroup are patients with
Brugada's syndrome who have a peculiar ECG
pattern consisting of a RBBB and ST segment
elevation in V1 to V3 - One study reported data on 63 such patients, 41
of whom were diagnosed after an episode of SCD - During a 34 month follow-up, a recurrent
arrhythmic event occurred in 34 percent of
symptomatic patients and in 27 percent of
asymptomatic patients
19Clinical Substrates Associated with VF Arrest
- Commotio cordis
- Sudden death has been described in young athletes
who have been struck in the precordium with a
projectile object such as a baseball, hockey
puck, or fist - One study described an animal model in which
low-energy blows to the chest wall delivered
during repolarization, just before the peak of
the T wave, produced ventricular fibrillation
20Clinical Substrates Associated with VF Arrest
- Family history
- A family history of myocardial infarction or SCD
is associated with an increased risk for SCD - Genetic abnormality
- A defect located on chromosome 1p1-1q1, has been
associated with sudden death - Affected individuals have progressive cardiac
conduction abnormalities and symptomatic sinus
bradycardia, requiring pacemaker therapy - Sudden death generally occurs beyond the age of
30 and is not prevented by pacemaker therapy
21OUTCOME OF RESUSCITATION
- When the initial rhythm is asystole, the
likelihood of successful resuscitation is low
and, when performed out of hospital, less than 10
percent survive to hospitalization - The outcome is much better when the initial
rhythm is a sustained VT (65 to 70 survival) - Approximately 25 percent of patients with VF
survive to be discharged in the majority of
these patients an acute myocardial infarction is
the underlying mechanism - Patients who have SCD due to PEA also have a poor
outcome
22FACTORS RELATED TO THE OUTCOME OF RESUSCITATION
- The only effective way to reestablish organized
electrical activity and myocardial contraction is
prompt electrical defibrillation - It has been estimated that organ damage becomes
irreversible after approximately 4 minutes of VF - As a result, the longer the duration of the
cardiac arrest, the lower the likelihood of
resuscitation or survival even if initial
resuscitation is successful
23FACTORS RELATED TO THE OUTCOME OF RESUSCITATION
- The Seattle Heart Watch program has reported on
the outcome of patients resuscitated at the scene
by a bystander trained in CPR compared with CPR
initiated by emergency medical personnel - There was no difference in the percentage of
patients resuscitated at the scene and admitted
alive to the hospital (67 versus 61 percent) - However, the percentage discharged alive was
significantly higher among those with
bystander-initiated CPR (43 versus 22 percent, plt
0.001)
24Bystander-initiated CPR Improves Outcome
25Causes of in-hospital mortality
- The cause of death in hospital is most often
noncardiac, usually being due to anoxic
encephalopathy or to respiratory complications
from long-term respirator dependence - Only about 10 percent of patients die from
recurrent arrhythmia, while approximately 30
percent die from a low cardiac output or
cardiogenic shock
26FACTORS RELATED TO THE OUTCOME OF RESUSCITATION
- In addition to later onset of CPR, there are a
number of other factors that are associated with
a poor outcome with CPR
- Cancer or Alzheimer's disease
- History of gt2 chronic diseases
- A history of cardiac disease
- Absence of any vital signs
- Sepsis
- An initial rhythm of asystole or PEA
- CPR lasting gt5 minutes
- CVA with severe neurologic deficit
27ACUTE THERAPY FOR THE SCD VICTIM
- The only effective approach for terminating VF is
defibrillation using 200 to 400 J of energy
delivered transthoracically in a nonsynchronized
fashion - The initial success of defibrillation depends
upon the duration of the arrhythmia and
promptness of defibrillation - When VF has been present for seconds to a few
minutes, the success rate is high
28ACUTE THERAPY FOR THE SCD VICTIM
- Intravenous amiodarone
- The ARREST trial (Amiodarone in the
Out-of-hospital Resuscitation of Refractory
Sustained Ventricular Tachyarrhythmias)
randomized 504 patients with a cardiac arrest due
to VF or pulseless VT who were not resuscitated
after at least three defibrillation shocks to
intravenous amiodarone (300 mg) or placebo - Survival to hospitalization was greater in the
amiodarone group (44 versus 35 percent) - Time to therapy with the study drug was an
independent predictor of survival to hospital
faster treatment was associated with a better
outcome - More than 50 percent of patients who survived to
discharge had no neurological impairment
29Evaluation of the survivor of SCD
- The evaluation begins immediately after
resuscitation - The first concern is to establish any obvious
provoking factors that may have led to the event
and which need to be corrected so as to prevent
an immediate recurrence - The patient or/and family should be questioned
about previous diagnoses of heart disease the
use of any medication, especially antiarrhythmic
agents, diuretics, or digoxin and antecedent
symptoms
30PROVOKING FACTORS
- Electrolyte disturbances
- Any reversible metabolic abnormalities should be
identified and corrected, particularly
hypokalemia and hypomagnesemia which may
predispose to ventricular tachyarrhythmias - Antiarrhythmic drugs
- Whenever possible, antiarrhythmic drugs should be
discontinued prior to any diagnostic studies
31PROVOKING FACTORS
- Use of an illicit drug such as cocaine can
directly cause arrhythmia or produce coronary
artery vasospasm and ischemia - A prolonged QT interval which may be acquired
(due, for example, to a drug or electrolyte
disturbance) or inherited
32CARDIAC EVALUATION
- It is essential that the patient undergo a
complete cardiac examination to establish the
nature and extent of underlying heart disease - The LV function and coronary anatomy should be
assessed utilizing physical examination, echo,
cardiac catheterization, and, if warranted,
myocardial biopsy - Since global LV dysfunction due to myocardial
stunning may be present as a result of the
cardiac arrest, baseline evaluation of left
ventricular function should be performed at least
48 hours after resuscitation
33ARRHYTHMIA EVALUATION
- There are different approaches (termed
conservative and aggressive) to the evaluation
and treatment of SCD - Ongoing controlled trials may in the future
provide information as to which of these
approaches is associated with the best outcome
34Conservative approach
- The conservative approach involves a complete
arrhythmia evaluation to establish at baseline
the type, frequency, and reproducibility of
spontaneous ventricular ectopy, and the
inducibility of a ventricular tachyarrhythmia - This involves the use of noninvasive ambulatory
monitoring for 48 hours, an exercise test, and an
invasive electrophysiologic study
35Conservative approach
- For patients with SCD, in whom sustained
monomorphic VT is induced at baseline, the use of
antiarrhythmic agents to prevent the induction of
sustained VT may be an adequate and effective
first approach - For those patients who have recurrent arrhythmia,
the ICD could be considered as an additional or
alternative therapy
36Aggressive approach
- The aggressive approach uses the ICD in all
victims of SCD whose chance of recurrence with
therapy cannot be accurately predicted - High, medium and low risk are all objective,
since recurrence of ventricular fibrillation is
often lethal
37Aggressive approach
- When using an aggressive approach, the value of
diagnostic testing is to find conditions that do
not require ICD insertion, like episodic
prolonged sinus arrest, severe AV nodal or
infranodal disease causing intermittent third
degree AV block, and preexcitation with AF
leading to VF - These and some other arrhythmias should be
treated with pacemaker, radiofrequency ablation
or therapies other than ICD
38Nonpharmacologic therapy in survivors of sudden
cardiac death
- RADIOFREQUENCY ABLATION
- There are a small number of sudden death
survivors in whom sustained monomorphic VT
appears to be the primary arrhythmia and in whom
a single, discrete arrhythmogenic focus can be
localized by electrophysiologic mapping - In such patients radiofrequency ablation is an
option for destroying the fixed anatomic lesion
responsible for the arrhythmia
39IMPLANTABLE CARDIOVERTER DEFIBRILLATOR
- The ICD is a well-established and highly
effective therapy for patients who have
experienced SCD - While a device does not prevent the arrhythmia,
it reverses it automatically and promptly when it
occurs - There are many reports showing an impressive
improvement in expected arrhythmia mortality
(ranging from one to five percent per year) in
patients who have received an ICD - However, there is still a substantial cardiac
mortality (approximately 5 to 10 percent per
year) as a result of progressive CHF
40IMPLANTABLE CARDIOVERTER DEFIBRILLATOR
- The ICD would not be expected to reduce death
from heart failure or non-cardiac causes what it
may do is shift the cause of death from sudden to
non-sudden cardiac death - As a result, the only appropriate endpoint is
total mortality which has now been reported in
three trials, CASH, CIDS, and AVID
41The Cardiac Arrest Survival in Hamburg (CASH
trial )
- German prospective randomized trial of ICD versus
antiarrhythmic drugs - In this study, patients were randomized to
receive an ICD, metoprolol, propafenone, or
amiodarone - In an interim two year analysis, the SCD rate was
lower with the defibrillator than with amiodarone
or metoprolol (0 versus 8 percent) - However there was no difference in total
mortality with the defibrillator, metoprolol, or
amiodarone (12 percent)
42The Canadian ICD Study (CIDS)
- 659 patients with VT, VF, or syncope deemed to be
secondary to arrhythmia were randomized to
amiodarone or an ICD - After a five-year follow up, the total mortality
with the ICD was reduced compared to amiodarone
(25 versus 30 percent, p0.072)
43The Antiarrhythmic Drug Versus Defibrillator
(AVID) trial
- Enrolled patients with a history of VT,VF, or
syncope judged to be secondary to arrhythmia - Survival benefit was noted in the 507 patients
receiving the ICD compared to the 509 patients
receiving sotalol or amiodarone - The unadjusted survivals for the ICD versus drug
groups were 89 versus 82 percent at one year, 82
versus 75 percent at two years and 75 versus 65
percent at three years - The total cost for the ICD was 27,500 more than
for drug therapy and the cost for additional year
of survival was 127,000
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