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Défibrillateurs Implantables pour Prévenir la Mort Subite-Pour Qui et Comment?
Paul Dorian, MD
Hôpital St Michel, Toronto
Patient ER (FV spontanée)
History of the AICD
1966- Dr. M. Mirowskiconceives the idea of an implantable defibrillator after his friend, colleague and mentor Dr. Harry Heller dies of sudden cardiac deathDr. Michel MirowskiDr. Michel Mirowski
(1924-1990)(1924-1990)The Inventor of the AICDThe Inventor of the AICD
History of ICD Therapy
• 1975 - The first device is implanted and tested in an animal
• 1980 - The first patient is implanted with an AICD device
Small devices – Pectoral site Transvenous, single incision
Local anesthesia; conscious sedation
hospital stay usually 0-1 days
Few complications ( similar to pacemakers_)
Perioperative mortality < 0.5%
Programmable therapy options
Single- or dual-chamber therapy
Battery longevity up to 9 years
ICD’s Today ( 2004)
Recognizes VT and VF – 99%
Terminates VT and VF – 99%
Pacemaker
Anti-tachycardia pacing therapy
Antitachycardia Pacing (ATP)
Shock (cardioversion)
The Penalty for Failure is DeathFu Manchu
Relation between Relation between triggers triggers and substrate in SCDand substrate in SCDRelation between Relation between triggers triggers and substrate in SCDand substrate in SCD
Big Trigger Trigger Small trigger
Good EF Substrate Poor EF
IschemiaTachycardiaAdrenergic drive
NSVTlightning VPB, EAD
The substrate is DYNAMIC
Categories of ICD indications
“Secondary prophylaxis” :
Patients with a prior history of sustained VT or VFNo reversible factors ( eg acute MI)
“Primary prophylaxis” :
Patients with no history of sustained VT or VFRisk factors for sudden death - severe LV dysfunction
- Heart failure symptoms - Non sustained VT ? - inducible VT at EP study?
Number at risk:ICD: 934 715 467 273 159 104 934 715 467 273 159 104Amio: 932 664 427 248 128 82 932 664 427 248 128 82
Meta-Analysis of ICD Secondary Prevention Trials: AVID, CASH, CIDS
6543210
50
40
30
20
10
06543210
50
40
30
20
10
0
Years Years
Death Arrhythmic Death
AmioAmio
ICDICD
AmioAmio
ICDICD
Connolly et al. Eur Heart J 2000;21:2071-8
Pts with prior sustained VT or VF
Long term follow up of Patients Treated with Amiodarone in CIDS
(SMH, n=60)
Time (Years)
121086420
100
80
60
40
20
0
Freedom From Event
(%)
Mortality
Mortality or Recurrence of Arrhythmia
Mortality, Recurrence of Arrhythmia or Discontinuation of Amiodarone Due to Side Effects
Bokhari et al Circ. 2004
MUSTT Study: CAD, EF < 40% , NSVT ( > 4d post MI), inducible VT/VF
Buxton AE. N Engl J Med. 1999;341:1882-90.
Time after Enrollment (Years)
0 1 2 3 4 5
0.1
0.2
0.3
0.4
0.5
0.6
Mo
rtal
ity
Rat
e
p < 0.001
EP-Guided Rx, No ICD
No EP-Guided AA Rx
EP-Guided Rx, ICD
(17% < 1mo, 22% 1mo-1 yr post MI)
Not randomized
MADIT-II : ICD’s for patients with prior MI and EF < 30%, no prior arrhythmias
Moss AJ. NEJM 2002;346:877-83.
Defibrillator
Conventional
P = 0.007
1.0
0.9
0.8
0.7
0.6
0.0
Pro
ba
bil
ity
of
Su
rviv
al
0 1 2 3 4Year
No. at Risk
Defibrillator 742 502 (0.91) 274 (0.94) 110 (0.78) 9
Conventional 490 329 (0.90) 170 (0.78) 65 (0.69) 3
QRS Prolongation: A Strong Independent Risk Factor for Mortality in Patients with Severe Ischemic Heart disease
QRS Duration, ms
Mortality, %
<100 (n=58)
13.8
100-119 (n=86)
17.6
120-139 (n=65)
23.6
140-159 (n=44)
45.5
140 (n=60)
43.3
Kalahasti V et al, PACE 2002;24:528
Noninvasive ECG Parameters in Multivariate Cox Model for Predicting Total Mortality in MADITT II Patients Randomized to Conventional Therapy
Variable
Age ≥ 65 yearsNYHA ≥ IIBUN > 25No BB use
AFibQRS > 0.12 sec
HR
1.472.001.941.572.361.90
(95% CI)
(0.86-2.52)(1.20-3.34)(1.17-3.21)(0.94-2.66)(1.14-4.89)(1.14-3.14)
P value
0.1640.0080.0100.0890.0210.013
Zareba et al, NASPE 2002
Survival in Defibrillator Group and Conventional Treatment Group in 364 MADITT II Patients with
QRS > 0.12 sec (excluding paced patients)
MORTALITY
2-yr
36%14%
3-yr
53%21%
ConvICD
HR = 0.37 (p=0.004) 63% reduction in mortalityZareba et al NASPE 2002
SCD HeFT-Enrollment Scheme
DCM ± CAD and CHF
EF ≤ 35%
NYHA Class II or III
6 minute walk, Holter
Placebo Amiodarone ICD
R
n=847 n=845 n=829
Mortality by Intention to Treat
ICD pts – 5%/yr risk of appropriate shock
28.9%
35.8%34.1%Amiodarone vs. Placebo
ICD Therapy vs. Placebo
HR1.060.77
97.5% CI0.86, 1.300.62, 0.96
P-Value0.5290.007
No Technology is perfect
• Inappropriate shocks
• Lead fracture. Dislodgement
• Infection
• Short battery life ( 5-7 years)
• Complex programming and follow-up
• Doesn’t prevent all sudden death
ICDs in SCD-HeFT
• 2.2% not implanted
• 4.0% removed, not replaced
• 4.6% serious complications at implant, no deaths
• 9.4% serious complications in follow-up
• 5.0% appropriate shocks / pt / yr
• total: 7.4% shocks / pt / yr
CABG Patch : ICD immediately after CABG EF <35%, +ve SAECG
Bigger JT. NEJM 1997;337(22):1569-1575.
30
20
10
0
Cu
mu
lati
ve M
ort
alit
y (%
)
Month
Defibrillator Group
Control Group
p = 0.64
24%
27%
12 24 36 48
Defibrillator Gr. 446 384 313 213 61
Control Group 454 399 308 199 57
Early post MI ICD vs control: All-Cause Mortality
DINA ITDINA IT
0 6 12 18 24 30 36 42 48
0.0
0.05
0.10
0.15
0.20
0.25
Months from Randomization
Cum
ula
tive R
isk
of
Death
318 305 272 217 172 124 79 31Cntrl315 299 258 211 172 123 82 25ICD
Number at Risk
ICDControl
0 6 12 18 24 30 36 42 48
0.0
0.05
0.10
0.15
0.20
0.25
Months from Randomization
Cum
ula
tive R
isk
of
Death
318 305 272 217 172 124 79 31Cntrl315 299 258 211 172 123 82 25ICD
Number at Risk
ICDControl p=0.66
Day 6-40 post MI, EF < 35%, depressed HRV
Months
Why Don’t ICDs Save Everyone From Dying a Sudden Death?
Some patients die from CHF or MI or Asystole / PEA
Some VT / VF is a precursor to non-arrhythmic death
Some VT / VF presents as electrical storm - electrical success, but poor outcome
2437
4454
63
84
105
132
154
180
208
2.5 4 6 8 10 14 18 22 27 3138 44
31
0
50
100
150
200
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
AnnualICD
implantsper millioninhabitants
ICD Implant Rates continue to diverge between Europe and USA
MADIT & AVID
Europe
USA
MUSTT
Updated from Nisam S, 2000
MADIT II???
CANADA*
The Real Questions in Deciding on ICD Recommendation
• What is the annual risk of sudden arrhythmic death?
(or the risk / device lifetime, ~ 5 years)
• What is the annual risk of death from other causes?
All ICDs are Prophylactic
MERCI