Electrical Storm: Managing Mayhem
Mark A. Wood, MD
CCU Conference 11.8.11
“Electrical Storm”
“Electrical Storm” defined as > 2 or > 3 VT
episodes treated by ICD within a 24 hour period
 Electrical Storm occurs in 10 – 20% of ICD
patients
 Important because:
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May be immediately life threatening
Management may be difficult
May influence prognosis
Has pathophysiologic implications for VT initiation
Mechanism of Electrical Storm
 Name
implies a dramatic departure from
“normal” pattern of VT recurrences
 “Normal” pattern of VT recurrences is
relevant to description of electrical storm
but overlooked
 VT recurrences are actually clustered in
time in most patients
Single Patient with 11 Episodes of VT
Detected Over 197 Days
Wood MA et al. Circulation 1995
2 detections
4 detections
2 detections
Time Between Ventricular Arrhythmias
Wood et al. J Cardiovasc Electrophysiol 2005
N = 71 patients
83% episodes < 1 hour
apart
A Method Among Madness?
The Power Law Distribution
Liebovitch, Wood et al. Physical Review E 1999
730 VT detections
PDF(t) = t -a
Log PDF
in 31 patients
Log Inter-Detection Interval
Long Term Patterns of
Arrhythmia Recurrences
 Recurrences
are not randomly distributed
over time
 Ventricular arrhythmia recurrences
described by Power Law or Weibull
distributions in 85% patients
 Time between arrhythmias < 1 hr for 83%
inter-detection intervals
Electrical Storm
“Real
Storm”
Electrical
Storm
“Normal”
Distribution
Sprinkle?
Pathophysiology of Electrical Storm
Why Do Events Cluster in Time?
 Transient
Metabolic/Electrical states
lasting hours or days
 Ventricular tachycardia is proarrhythmic
Pathophysiology of Arrhythmia Initiation
A Confluence of Metabolic States?
CRITICAL CONFLUENCE
OF FACTORS - PERIOD OF
HIGH PROBABILITY
Cumulative Risk
VT Likely
VT Unlikely
TIME
Pathophysiology of Arrhythmia Initiation
VT is Proarrhythmic
Tsuji Y et al. Circulation
2011

Rabbit model electrical
storm (CHB and ICD)
 Spontaneous electrical
storm associated with
abnormal Ca handling
 Ca abnormalities
reproduced by repeated
VF induction not shocks
Mathematical Model of VT Recurrences
Sedaghat H, Wood M
•Computer model includes electrical
properties of reentry circuit
•Simulates months of heart beats
•Spontaneous “VT” occurs due to
subtle “wobble” in circuit conduction
•Reentry leads to more reentry
Heart Disease in Electrical Storm
 Ischemic
 Non-Ischemic
 Valvular
 Brugada’s
Syndrome
 Arrhythmogenic Right Ventricular
Dysplasia
 Infiltrative disease (Sarcoid)
Clinical Causes of Electrical Storm
Unkown – approximately 66% cases
 Decompensated heart failure
 Acute ischemia
Approximately
 Metabolic disturbances
33% cases


T4, K, Mg, DKA

Drug proarrhythmia
 Drug overdose
 Fever (DCM and Brugada’s Syndrome)
 Post cardiac surgery
 ICD induced
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Bi V pacing or pacing induced
“Psuedo-Storm” - inappropriate therapies
Features of Electrical Storm
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Occurs in secondary and primary prevention
patients
Storm may be first therapies by ICD
52 - 90% Storm events are VT, 10 – 48% VF
Time to storm averages 4 – 47 months after
implant
Storms may be recurrent in same patient
Number of events 3 - 50 but extreme cases
reported
Door Prize Question:
What is the greatest number of
shocks reported during an
electrical storm?
The Ultimate Electrical Storm?
Management of Electrical Storm:
MMVT or PMVT?
Momomorphic VT
Think reentry
Polymorphic Ventricular Tachycardia
Ventricular Fibrillation
Think
metabolic,
drugs,
ischemia, brady
Predictors of Electrical Storm
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VT1,2 or VF 4 as indication for ICD
EF < 25%2,3
Chronic renal failure2
QRS >120 msec3
Absence beta blocker therapy3
Use of digoxin1
Absence of revascularization after index
arrhythmia1
1. Exner et al. Circ 2001
CAD4
2. Brigadeau et al. EHJ 2005
3. Arya et al. AJC 2006
4. Verma et al. JCE 2004
Management of Electrical Storm
 Search
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for reversible causes
Acute ischemia – cath
Metabolic/Electrolyte abnormalities – labs and
correct:
• Magnesium – even if normal serum level
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Heart failure/hypoxia:
• Oxygenate
• Reduce filling pressures/wall stress
• Reduce sympathetics by improved hemodynamics
Management of Electrical Storm
Medical Therapy
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Beta blockade – for ischemic heart dz
Amiodarone – widely used for everyone
Lidocaine – best for acute ischemia
Class III agents – Ibutilide off label
Class IA – procainamide, quinidine – may
slow VT
ICD Reprogramming
 Overdrive
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Prevent pause induced arrhythmias
Suppress PVCs
 Inactivate
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pacing;
proarrhythmic features
Bi V pacing
Fix sensing issues
Special algorithms
detection time – for NSVT
 Alter detection rate – For stable VT
 Turn on ATP, increase first shock
 Lengthen
ICD Reprogramming
Adjunctive Measures
 General

anesthesia
Propofol
 Left
stellate ganglion
ablation
 Emergent
radiofrequency ablation
Thorascopic Left Stellate Ganglion
Denervation
Percutaneous Stellate Ganglion Blockade
Abdi et al.Pain Physician 2004
Rescue Ablation in Electrical Storm
Schreieck J et al. Heart Rhythm 2005
Management of Electrical Storm
Brigadeau F et al. European Heart J 2006 – 123 patients
Verma et al. JCE 2004 – 208 patients
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Antiarrhythmic drug therapy: 48 – 91%
(Amiodarone)
No specific action – 29%
ICD reprogramming – 23%
Heart failure treatment – 16%
Ablation – 7%
Revascularization: 3 – 11%
Hyperthyroid treatment – 3%
Survival After Electrical Storm
Verma A et al. J Cardiovasc Electrophysiol 2004
Death during Storm is uncommon
No Storm
Storm
N = 208
Mortality After Electrical Storm
 Classification
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Deaths
Cardiac non-sudden: 46 - 56%
Non-cardiac: 20 - 32%
Sudden: 21%
 Increased
mortality after Storm likely
represents failing heart
Exner DV et al. Circulation 2001 and
Verma A et al. J Cardiovasc Electrophysiol 2004
Management After Storm
 Aggressive
re-vascularization
 Aggressive medical therapy
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Beta blockers
ACE and Aldosterone inhibitors, Statins
Antiarrhythmics
Electrolyte management
 Sedation
and post trauma care (PTSD)
Management After Storm
 Post
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Traumatic Stress
Poor QOL after shocks
Fear of activity/social situations
Anxiety/depression – medical Rx
Phantom Shocks/”Afraid to go to sleep” –
reassurance
Request removal of device – reassurance
Summary
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Electrical Storm not uncommon in ICD patients
VT recurrences tend to cluster in ICD patients
Most Storms without identifiable cause but heart
failure, ischemia and metabolic abnormalities
should be considered
Medical management usually effective
Storm probably associated with increased
subsequent mortality, aggressive management
may be indicated
Heard Enough?
Beta Blockade for Ischemic Electrical Storm
Nadamanee et al. Circ 2000
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49 patients with electrical
storm 10 + 11 day post
MI
Electrical Storm: >20
VT/24 hours
ACLS protocol:
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Lidocaine
Procainamide
Bretylium
No beta blocker
Sympathetic blockade
after initial ACLS protocol
LONG-TERM TEMPORAL PATTERNS OF
VENTRICULAR ARRHYTHMIAS
Wood M et al. Circulation 1995
83% of 31 patients
demonstrated
clustered distribution
Survival After Electrical Storm
Exner DV et al. Circulation 2001
 457 AVID patients receiving ICD
 Storm defined as > 3 ICD Rx/24 hours
 20% patients with Electrical Storm

60% patients > 1 ICD therapy
 Storm
independent risk subsequent death
RR = 2.4 (p =0.003)
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In 3 months after storm RR = 5.4 (p = 0.0001)
Beyond 3 months RR = 1.9 (p = 0.04)
SHIELD Study: Azimilide for VT Prevention in ICD Patients
Using Anderson-Gill Intensity Model
Dorian et al. Circulation 2004
Power Law Distribution for Atrial Tachyarrhythmias
Shehadeh, Wood et al. JCE 2004
10,759 AT detections in 63 patients
Survival After Electrical Storm
Death during Storm is uncommon but
No consensus on subsequent survival
N = 136
Credner SC et al. JACC 1998
Rescue Ablation in Electrical Storm
Schreieck J et al. Heart Rhythm 2005
5
patients ischemic cardiomyopathy
 Received 3 - 310 ICD shocks in 2 weeks
 3 – 8 VT morphologies
 Failed all medical and pacing therapies but
allowed elctroanatomic mapping VT
substrate
 At ablation pace mapping and targeting
delayed fractionated electrograms