Primary Prevention Of Sudden Cardiac Death - Role Of Devices

Dr Arindam Pande,
MBBS (Hons), MD, DM (Cardiology)
Consultant Cardiologist,
Academic Coordinator: DNB Cardiology and PGDCC Training
Apollo Gleneagles Hospital, Kolkata
“Primary Prevention Of Sudden
Cardiac Death - Role Of Devices”

Lets start with an case example…
• 64 year genleman
• Heavy smoker, T2DM, HTN
• Chest pain of 11 hours
• ECG – acute ASMI
• ECHO at ER reveals EF – 27%
• Ongoing chest pain
• Planned for Primary PCI

Follow up at 1.5 months
• No chest pain/angina
• Mild SOBE, NYHA Class 2
• Resumed normal activity
• BP – 120/70 mmHg,
• HbA1C – 6.2%
• Lipid profile and other biochemical
parameters – within normal limits
• ECHO: LVEF - 34%

Definition
 SCD is natural death from cardiac causes
heralded by abrupt loss of consciousness
within 1 hour (Rapid- interval between the
onset of symptoms to cardiac arrest) of the
onset of an acute change in cardiovascular
status
 Preexisting heart disease may or may not
have been known to be present, but the
time and mode of death are unexpected

# -Sudden Cardiac arrest - abrupt cessation of cardiac
mechanical function, which may be reversible with prompt
intervention but will lead to death in its absence
# -Sudden cardiac death -Sudden, irreversible cessation of all
biologic function

Prevention of cardiac arrest and
SCD
 Primary prevention
High risk patients of advanced heart disease with
low EF and other high risk markers
Less advanced common or uncommon structural
heart diseases
Structurally normal hearts, subtle or minor structural
abnormalities, or genetically based molecular
disorders that establish risk for ventricular
arrhythmias
General population
 Secondary prevention
Prevention of recurrent events in survivors of cardiac
arrest or pulseless VT or other symptomatic
tachycardias considered life-threatening

Strategies
 ICD
 Antiarrhythmic drugs
 Catheter ablation
 Antiarrhythmic surgery
 The choice of a therapy is based on
Estimation of risk of the individual patient
Available efficacy and
Safety data

30 days survival rates ranged from a maximum of 48% with responses
shorter than 2 minutes to less than 5% with response time longer than
15 minutes

Electrical mechanisms of cardiac
arrest
 Tachyarrhythmia
Ventricular fibrillation and
Pulseless sustained VT
 Bradyarrhythmias
Severe bradyarrhythmias (< 20
beats /min)
Pulseless electrical activity

In Summary
 SCD is not common
 About half of all cardiovascular deaths
 Approx. 50% of all SCDs are unexpected
first expressions of a cardiac disorder
 High-risk people usually identified by
symptoms or family history – priority for
evaluation
 Cure not possible, but correct management
can prevent complications

ICDs
 The first generation of defibrillators required a
thoracotomy to place the sensing and defibrillator
leads epicardially, and the generator size mandated
implantation of the device in an abdominal pocket
 Current-generation ICD integrate pacing, sensing,
and high-voltage defibrillation abilities
 have the additional ability to deliver low-energy
cardioversion, ATP for VT, and anti bradycardia pacing
 Given the excellent safety and good profile of
current ICD, implantation is not a major challenge
 Identification of patient populations most appropriate for
this potentially lifesaving therapy

Randomised Trials of ICD
Therapy
“Primary prevention” - patients who
have not yet had VT or VF, but are
thought to be at high risk
 Multicenter Automatic Defibrillator
Implantation Trial (MADIT 1) -1996
 Multicenter UnSustained Tachycardia Trial
(MUSTT) - 1999
 MADIT 2 – 2002
 COMPANION – 2004
 SCD-HeFT - 2004

5 10 20 30
CATCAT
CABG-PatchCABG-Patch
MUSTTMUSTT
MADIT IMADIT I
ns VTns VT
High riskHigh risk
no VAno VA MADIT IIMADIT II
DINAMITDINAMIT
SCD-HeFTSCD-HeFT
DEFINITEDEFINITE
LV-EF (%)LV-EF (%)
ICD Trials - Primary
prophylaxis

ICD 10
Prevention Trial Results
CABG-Patch
MUSTT
MADIT I
MADIT II
DINAMIT
SCD-HeFT
DEFINITE
AMIOVIRT
CAT
0 0.5 1 1.5 2 2.5
CAD, MI
NICM
CAD,
NICM
Hazard Ratio
ICD better No ICD better

Overview of Primary Prevention
Trials Results
MADIT 54% reduction in mortality with ICD
MUSTT 55-60% reduction in mortality with
ICD
MADIT II 31% reduction in mortality with ICD
DEFINITE Mortality benefit 5.7% at 2 years
with ICD
SCDHeFT 23% reduction in mortality with ICD

Risk stratification for sudden death
in ICD trials
• Ejection fraction
(EF <30%, <35%, <40% + ...)
• Etiology of depressed EF
(CAD vs DCM)
• EP study
(inducible VT, VF)
• Timing of remote myocardial infarction
(< 40 days, > 40 days / 1 month)
• [HRV]
• NYHA class
• QRS duration

LV-EF is considered as the best
parameter for risk stratification
after MI
exponential increase of risk of
SCD below EF 35-40%
LV-EF (%)
risk
LV-function as predictor of
SCD
MUSST, MADIT, MADIT-2, SCD-HeFT
DINAMIT, COMPANION, ………

MADIT Trial
 1st
RCT comparing AADs (Amiodarone)
& ICD
 This trial included post MI > 1 month
EF < 35%
NSVT during ambulatory recording and
inducible VT that was not suppressible by IV
procainamide
 This very high-risk group demonstrated
a 54% reduction in total mortality with
ICD therapy versus drug therapy
Moss et al N Engl J Med 1996; 335: 2933-40

MADIT - Results
Moss et al N Engl J Med 1996; 335: 2933-40

Multicenter unsustained tachycardia
trial (MUSTT)
 Assess to identify NSVT In post MI with
other risk markers for early mortality
EF < 40%.
Inducible VT
Ambient NSVT
 The results demonstrated a statistically
significant beneficial effect on total
mortality (subgroup who not responded)

MUSTT - Results
Buxton et al. N Engl J Med 1999 ;341:1882-90

ICD Trials: Why is the benefit greater in
“Primary Prevention” studies?
 In AVID, CASH and CIDS, the main entry
criterion was ventricular arrhythmia
Some patients had preserved LV function
Mortality reduction with ICD 28% overall
Mortality reduction 34% in patients with LVEF <
35%
 In MADIT and MUSTT, the main entry
criterion was poor LV function
LVEF <35% in MADIT, <40% in MUSTT
Mortality reduction with ICD 54 - 60%
Heterogeneity in antiarrhythmic drug use

Who benefits most from
ICDs?
1990’s
 Patients at highest risk
of sudden death are
those with ventricular
arrhythmias
(spontaneous or
induced)
 The ICD is a treatment
for ventricular
arrhythmias
2000’s
 Patients at highest risk
of sudden death are
those with heart failure
due to poor LV systolic
function
 The ICD is a
treatment for heart
failure

MADIT II trial
 Survival benefit of ICDs in patients of post MI with
rEF -30%
 NYHA II & III
 No arrhythmic markers for inclusion
 A total 1232 patients in a 3 : 2 ratio ICD (742) or
conventional medical therapy (490). Av EF- 23%
 An Av follow-up of 20 months
 All-cause mortality rates were 19.8% in the conventional
arm and 14.2% in the ICD group (31% RRR, P = 0.016)
 The findings suggested that HF patients with mild to
moderate symptoms and moderate to severe
reductions in LVEF may benefit the most from a
prophylactic ICD as early as 9 months

MADIT II Results
Moss et al New Engl J Med 2002; 346: 877-883

MADIT- II
Subgroup analyses and additional tests
 Heart rate variability (several
parameters), signal averaged ECG - not
useful
 EP study performed in those with ICD
If EP +ve, more likely to get VT
If EP -ve, more likely to get VF !
Overall limited usefulness
 QRS width - powerful predictor of benefit
from ICD

Moss et al New Engl J Med 2002; 346: 877-883
MADIT II - Subgroup analysis

Defibrillator in Acute Myocardial
Infarction Trial (DINAMIT)
 It was designed to evaluate any possible
benefit of ICD early after MI
Total 674 patients with
Recent (6-40 days) MI
EF < 35%, depressed HRV
Mean 24-hour HR > 80/min
Tested ICD/ no ICD
 ICDs do not appear to be of benefit
immediately after large MI (unexplained
increase in non arrhythmic death)

Defibrillator implantation in
nonischemic CMP (DEFINITE) trial
 1st
RCT of primary prevention therapy with
an ICD in patients with non ischemic CMP
EF of 35% or less, a history of symptomatic HF
Ambient arrhythmia defined as an episode of
NSVT or at least 10 PVCs per 24-hour period
during continuous ambulatory ECG
 229 patients to each arm of the study
ICD + standard medical therapy/standard
medical therapy alone

DEFINITE trial
 Follow -29.0+-14.4 months with primary endpoint all-
cause mortality
 Total 68 deaths were reported
 28 in the ICD group and
 40 in the standard therapy group
 ICD yielded
 Non-significant 35% reduction in death from any cause (P =
0.08)
 Significantly reduced the risk for SCD by a remarkable 80%
(P = 0.006)
 In the subgroup of NYHA class III patients, all-cause mortality
was significantly decreased in the ICD arm (P = 0.02)
 The results demonstrated a strong trend toward a
survival advantage for patients receiving an ICD

Sudden Cardiac Death–
Heart Failure Trial
 This landmark RCT addressed two
important issues
(1) Whether empiric Amiodarone therapy saves
lives in well-treated patients with NYHA class II
and III
(2) Whether a prophylactic ICD saves lives
 Total 2521 patients
NYHA class II (70%) or III (30%)
LVrEF (≤35%; mean, ≈25%)
Ischemic or nonischemic
SCD-HeFT trial had 3 arm ICD/Amiodarone/
placebo

Sudden Cardiac Death–
Heart Failure Trial
 The median follow-up was 45.5 months
 An ICD was associated with a
statistically significant 23% reduction in
all-cause mortality in comparison to
placebo ( P = 0.007)
 Mortality in the amiodarone arm was not
significantly different from that in the
placebo arm across all subgroups

SCD and ICD Summary
SCD – THE leading cause of death in the US
and whole world
ICDs superior to optimal medical mgmt alone as
demonstrated in multiple clinical trials
Patients at risk need to be identified before they
have SCD
 KNOW YOUR PATIENT’S EF !!!!
ICDs are cost-effective and underutilized
ICD therapy can be painless
The mortality risk of NOT having an ICD far
outweighs the risk of device failure

Guidelines
 Current ACC/AHA/HRS
guidelines for ICD

ICD
Class I
 VT/VF survivors with irreversible etiology
 sustained VT with structural heart disease
 syncope + VT/VF at EPS
 NYHA II-III, LV EF<35%
 NYHA I, post-MI, LV EF<30%
 NSVT, post-MI, LV EF<40%, VT/VF at EPS

ICD
Class IIa
 syncope, LV dysfunction, non-ischemic
DCM
 Sustained VT
 HCM with major risk factors
 ARVD with major risk factors
 LQTS with syncope while on BB therapy
 transplant bridge
 Brugada syndrome with syncope or VT
 Catecholaminergic polymorphic VT with
syncope

ICD
Class IIb
 NYHA I, LV EF<35%
 LQTS and SCD risk factors
 idiopathic syncope and advanced SHD
 familial CMP
 LV noncompaction

ICD
Class III
 Expected survival less than 1 year (other
cause)
 Incessant VT/VF
 Significant psychiatric illness
 NYHA IV without transplant or CRT indication
 Idiopathic syncope with no inducible VT/VF
and SHD
 VT/VF amenable with ablation
 VT/VF with reversible cause

Take home message..
 ICD is most cost effective when used for patients at‑
high risk of arrhythmic death and low risk of other‑ ‑
causes of death.
 Specific patient populations are now recognized for
whom the benefit of ICD therapy outweighs any risks
 Categorizing patients on the basis of only LVEF and
NYHA Functional Class can aid in identification of
patients who have highest benefit from primary
preventions

Primary Prevention Of Sudden Cardiac Death - Role Of Devices

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Primary Prevention Of Sudden Cardiac Death - Role Of Devices