Download Ventricular Tachycardia (VT) and Sudden Cardiac Arrest (SCA)

Ventricular Tachycardia (VT)
and
Sudden Cardiac Arrest (SCA)
-Epidemiology, Etiology and
Evaluation
Thomas J Dresing, MD
Cleveland Clinic
Objectives
•
•
•
•
•
•
What is SCA
Define incidence of SCA
SCA and Post-MI patients
SCA and HF patients
Landmark trials
How to identify patients for primary
prevention
Sudden Cardiac Arrest is one of the
Leading Causes of Death in the U.S.1-3
335,000
SCA3
41,400
Breast
Cancer1
1
14,000
AIDS2
American Cancer Society. Cancer Facts and Figures 2006.
CIA. The World Factbook – rank Order – HIV/AIDS – deaths. Available at: http//www.cia.gov
3 American Heart Association. 2005 Heart and Stroke Statistics Update.
2
162,500
Lung Cancer1
Only ALL cancers combined causes more deaths
each year than sudden cardiac arrest.
Septicemia
Nephritis
Alzheimer’s Disease
Influenza/Pneumonia
Diabetes
Accidents/Injuries
Chronic Lower Respiratory Diseases
Cerebrovascular Disease
Other Cardiac Causes
Sudden Cardiac Arrest (SCA)
All Cancers
National Vital Statistics Report, Vol 49 (11), Oct. 12, 2001.
State-specific mortality from sudden cardiac death – United States 1999. MMWR. 2002;51:123-126.
20%
25%
Cause of SCA
12%
Other Cardiac
Cause
88%
Arrhythmic
Cause
Albert CM. Circulation. 2003;107:2096-2101.
Underlying Arrhythmias of SCA
Torsades de Pointes
13%
Bradycardia
17%
VT
62%
Primary VF
8%
B Adapted from Bayes de Luna A. Am Heart J. 1989;117:151-159. ayés de Luna A. Am Heart J. 1989;117:151-159.
Who is at Risk for SCA?
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•
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A prior SCA
Family history of SCA
Congestive Heart Failure (CHF)
Have had a Myocardial Infarction (MI)
Ejection Fraction (EF) less than or
equal to 35%
Sudden Cardiac Arrest Risk
How can we
effectively identify
patients at-risk?
SCD-HeFT,
MADIT II
AVID, CASH
MADIT I, MUSTT
Myerburg RJ, et al. Circulation. 1998. 97:1514-1521.
Epidemiology of VT & SCA
Classification of Ventricular Arrhythmia
By Disease Entity
•Chronic coronary heart disease
•Heart failure
•Congenital heart disease
•Neurological disorders
•Structurally normal hearts
•Sudden infant death syndrome
•Cardiomyopathies
♥ Dilated cardiomyopathy
♥ Hypertrophic cardiomyopathy
♥ Arrhythmogenic right ventricular (RV)
cardiomyopathy
Audience Response Question #1
Who is at Risk for SCA?
A. A patient with a prior SCA
B. A patient with a family history of SCA
C. A patient with Congestive Heart
Failure (CHF)
D. A patient who has had a Myocardial
Infarction (MI)
E. All of the above
Audience Response Question #1
Who is at Risk for SCA?
A. A patient with a prior SCA
B. A patient with a family history of SCA
C. A patient with Congestive Heart
Failure (CHF)
D. A patient who has had a Myocardial
Infarction (MI)
E. All of the above
Epidemiology of VT & SCA
Classification of Ventricular Arrhythmia
By Electrocardiography
•Nonsustained ventricular tachycardia (VT)
♥ Monomorphic
♥ Polymorphic
•Sustained VT
♥ Monomorphic
♥ Polymorphic
•Bundle-branch re-entrant tachycardia
•Bidirectional VT
•Torsades de pointes
•Ventricular fibrillation
Nonsustained Monomorphic VT
Nonsustained Polymorphic VT
Sustained Monomorphic VT
Spontaneous conversion to NSR (12-lead ECG)
Sustained Polymorphic VT
Bundle Branch Reentrant VT
VF with Defibrillation (12-lead ECG)
Clinical Presentations of Patients
with VT & SCA
•Asymptomatic individuals with or without electrocardiographic
abnormalities
•Persons with symptoms potentially attributable to ventricular
arrhythmias
♥ Palpitations
♥ Dyspnea
♥ Chest pain
♥ Syncope and presyncope
•VT that is hemodynamically stable
•VT that is not hemodynamically stable
•Cardiac arrest
♥ Asystolic (sinus arrest, atrioventricular block)
♥ VT
♥ Ventricular fibrillation (VF)
♥ Pulseless electrical activity
The most common mode of death
in mild to moderate CHF is SCA
NYHA II
12%
24%
64%
NYHA III
CHF
CHF
Other
26%
Other
15%
Sudden
Death
59%
Sudden
Death
n = 103
n = 103
SCA
Pump Failure
NYHA Class II
64%
12%
NYHA Class III
59%
26%
People who’ve had a heart attack have a
sudden death rate that’s 4-6 times that of
the general population
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Studies show that a previous MI can be identified
in as many as 75% of SCA patients
A previous MI raises the one-year risk of SCA by
5% as a single risk factor
The five-year risk of SCA for patients with a
previous MI, non-sustained, inducible, nonsuppressible VT, and a LVEF < 40% is 32%
Reduced left ventricular ejection fraction (LVEF)
remains the single most important risk factor for
overall mortality and sudden cardiac arrest
No PVCs
Maggioni AP. Circulation. 1993;87:312-322.
1.00
1.00
> 10 PVCs/hr
0.98
p log-rank 0.002
0.96
Survival
0.96
Survival
1-10 PVCs/hr
0.94
0.92
0.94
0.92
0.90
0.90
0.88
0.88
p log-rank 0.0001
A
B
0.86
0.86
0
30
60
90
120
150
180
Days
0
30
60
90
120
150
Days
Patients without LV Dysfunction
Patients with LV Dysfunction
(LVEF >35%)
(LVEF < 35%)
180
SCA in Heart Failure1,2
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1
Despite improvements in medical
therapy, symptomatic HF still confers
a 20-25% risk of pre-mature death in
the first 2.5 yrs after diagnosis.
 50% of these premature deaths
are SCD (VT/VF)
Bardy G. The Sudden Cardiac Death-Heart Failure Trial (SCD-HeFT) in Woosley RL, Singh S. Arrhythmia Treatment and Therapy. Copyright 2000 by
Marcel Dekker, Inc. , pp. 323-342,
2 Sweeney MO. PACE. 2001;24:871-888.
Audience Response Question #2
True or False?
The most common cause of death in a
patient with mild to moderate CHF is
“pump failure”.
Audience Response Question #2
True or False?
The most common cause of death in a
patient with mild to moderate CHF is
“pump failure”.
FALSE
Surviving SCA
Urgency of Sudden Cardiac Arrest
Resuscitation Success vs. Time
Chance of success
reduced 7-10% every
minute
100
90
80
%
Success
70
60
50
40
30
20
Adapted from text: Cummins RO,
1998. Annals of Emergency
Medicine. 18:1269-1275..
10
0
1
2
3
4
5
6
Time (minutes)
7
8
9
Sudden Cardiac Arrest
SCA Survival = Early Defibrillation
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Only effective treatment for SCA is an
electrical shock delivered by:
- Automated external defibrillator (AED) or
- Implantable cardioverter-defibrillator
(ICD)
Time is critical – each minute of delay
before defibrillation reduces survival rates
by about 10%
Therapies for VT
Antiarrhythmic Drugs
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♥ Beta Blockers: Effectively suppress ventricular ectopic beats &
arrhythmias; reduce incidence of SCD
♥ Amiodarone: No definite survival benefit; some studies have shown
reduction in SCD in patients with LV dysfunction especially when given
in conjunction with BB. Has complex drug interactions and many
adverse side effects (pulmonary, hepatic, thyroid, cutaneous)
♥ Sotalol: Suppresses ventricular arrhythmias; is more pro-arrhythmic
than amiodarone, no survival benefit clearly shown
♥ Conclusions:
Antiarrhythmic drugs (except for BB) should
not be used as primary therapy of VA and the prevention of
SCD
Therapies for VT
Non-antiarrhythmic Drugs
♥ Electrolytes: magnesium and potassium administration can favorably
influence the electrical substrate involved in VA; are especially useful in
setting of hypomagnesemia and hypokalemia
♥ ACE inhibitors, angiotensin receptor blockers and aldosterone blockers can
improve the myocardial substrate through reverse remodeling and thus reduce
incidence of SCD
♥ Antithrombotic and antiplatelet agents: may reduce SCD by reducing
coronary thrombosis
♥ Statins: have been shown to reduce life-threatening VA in high-risk patients
with electrical instability
♥ n-3 Fatty acids: have anti-arrhythmic properties, but
conflicting data exist for the prevention of SCD
Therapies for VT
ICDs: Results from Primary and Secondary Prevention Trials
Hazard ratio
Trial Name, Pub Year
LVEF, other features
N = 196
MADIT-I
1996
0.35 or less, NSVT, EP
positive
0.46
AVID
1997
N = 1016
Aborted cardiac arrest
0.62
CABG-Patch
1997
N = 900
0.35 or less, abnormal
SAECG and scheduled for
CABG
1.07
N = 191
CASH*
2000
Aborted cardiac arrest
0.83
CIDS
2000
N = 659
Aborted cardiac arrest or
syncope
0.82
MADIT-II
2002
0.30 or less, prior MI
N = 1232
0.69
DEFINITE
2004
0.35 or less, NICM and
PVCs or NSVT
N = 458
0.35 or less, MI within 6 to 40
days and impaired cardiac
autonomic function
0.65
N = 674
DINAMIT
2004
1.08
0.35 or less, LVD due to prior
MI and NICM
N = 1676
SCD-HeFT
2005
0.77
0.4
0.6
ICD better
0.8
1.0
1.2
1.4
1.6
1.8
Major Implantable Cardioverter-Defibrillator Trials for Prevention of
Sudden Cardiac Death
Trial
Year
Patients
(n)
Additional Study
Features
LVEF
Hazard
Ratio*
95% CI
p
MADIT I
1996
196
< 35%
NSVT and EP+
0.46
(0.26(0.26-0.82)
p=0.009
MADIT II
2002
1232
< 30%
Prior MI
0.69
(0.51(0.51-0.93)
p=0.016
CABGCABG-Patch
1997
900
< 36%
+SAECG and CABG
1.07
(0.81(0.81-1.42)
p=0.63
DEFINITE
2004
485
< 35%
NICM, PVCs or NSVT
0.65
(0.40(0.40-1.06)
p=0.08
DINAMIT
2004
674
< 35%
6-40 days postpost-MI
and Impaired HRV
1.08
(0.76(0.76-1.55)
p=0.66
SCDSCD-HeFT
2006
1676
< 35%
Prior MI of NICM
0.77
(0.62(0.62-0.96)
p=0.007
AVID
1997
1016
Prior cardiac
arrest
NA
0.62
(0.43(0.43-0.82)
NS
CASH†
CASH†
2000
191
Prior cardiac
arrest
NA
0.766
‡
1-sided
p=0.081
CIDS
2000
659
Prior cardiac
arrest, syncope
NA
0.82
(0.60(0.60-1.1)
NS
* Hazard ratios for death from any cause in the ICD group compared with the non-ICD group. Includes only ICD and amiodarone patients from CASH.
‡CI Upper Bound 1.112 CI indicates Confidence Interval, NS = Not statistically significant, NSVT = nonsustained ventricular tachycardia, SAECG = signal-averaged electrocardiogram.
Epstein A, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. J Am Coll Cardiol 2008; 51:e1–62. Table 5.
Implantable Cardioverter Defibrillators
(ICDs) Restore Heart Rhythm
First-line therapy for patients at
risk for SCA
• ICD therapy consists of pacing,
cardioversion, and defibrillation
therapies to treat
tachyarrhythmias. ICDs also have
programmable diagnostic
functions.
• An ICD system includes the
device, and the pacing, sensing
and defibrillation lead(s).
SCA Can Be Prevented…
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The majority of cases are in patients with:
– Coronary artery disease, previous MI
– Low left ventricular ejection fraction
– Dilated cardiomyopathy and heart failure
Defibrillation is the only effective treatment option
High-risk patients can be evaluated for known risk
factors before they experience a Sudden Cardiac
Arrest
• EF remains a key indicator
Audience Response Question #3
In which of the following patients is a
defibrillator indicated?
A. A 74 YO female with a history of coronary
artery disease and a severely reduced ejection
fraction (EF)
B. A 25 YO male with vasovagal syncope and
PVC’s
C. A 82 YO male with metastatic lung cancer and
CHF with an EF of 35%
D. A 65 YO female with CAD and EF 45-50% who
cannot take beta blockers due to fatigue or
ACE-I due to cough
Audience Response Question #3
In which of the following patients is a
defibrillator indicated?
A. A 74 YO female with a history of coronary
artery disease and a severely reduced ejection
fraction (EF)
B. A 25 YO male with vasovagal syncope and
PVC’s
C. A 82 YO male with metastatic lung cancer and
CHF with an EF of 35%
D. A 65 YO female with CAD and EF 45-50% who
cannot take beta blockers due to fatigue or
ACE-I due to cough
Conclusions
The key to SCA prevention is to identify
high risk patients BEFORE they have a
SCA event. The majority of cases are in
patients with:
 Coronary artery disease, previous MI
 Low left ventricular ejection fraction
 Dilated cardiomyopathy and heart failure