Pre-excitation Syndromes is a group of ECG and Electrophysiological abnormalities in which The atrial impulses are conducted partly or completely, PREMATURELY, to the ventricles via a mechanism other than the normal AV-node * Associated with a wide array of tachycardias with both normal QRS and prolonged QRS durations

1. Pre-excitation syndromes in
children
Dr.K.Mahesh

2. Introduction

3. What are “Pre-excitation syndromes” ?
• Term coined by Ohnell
• A group of ECG and Electrophysiological
abnormalities in which
– The atrial impulses are conducted partly or
completely, PREMATURELY, to the ventricles
via a mechanism other than the normal AV-
node *
– Associated with a wide array of tachycardias
with both normal QRS and prolonged QRS
durations
*Moss & Adams

4. Re-entrant Vs Automatic
Tachycardias
• RE-ENTRANT
– V. regular
– Abrupt onset/cessation
– Easily initiated
– Easily terminated
– Responsive to drugs
• AUTOMATIC
– Wide variation
– “Warm-up, cool-down”
– Not so
– Not so
– Atypical responses
SAN SAN re-entry
Atria IART / flutter, AT fibrillation EAT, MAT
AVN AVNRT JET
Venticle VT Focal VT
Acc
Pathways
ORT (WPW), ORT (URAP), ORT
(PJRT), ART (WPW), ART (Mahaim)

5. Origin of the Accessory pathways ?
• In early stages of cardiac development,
there is direct physical and electrical
contact between the atrial and ventricular
myocardium
• ….disrupted by susequent in-growth of the
AV sulcus tissue and formation of the
annulus fibrosus
• Defects in this annulus results in
accessory pathhways

6.  Most of these connections are of
ventricular myocardial origin, rather
than of atrial issue origin
 May be found anywhere across the
tricuspid or mitral valve annulus –
whether endocardial or epicardial
 Most common pathways in children
are Left Free Wall followed by
Posteroseptal and Right Free Wall ;
Midseptal and Anteroseptal are least
common *
*Calkin et al, Circulation 1999

7. • AP mediated SVTs account for > 70% of
all SVTs in children who have not
undergone surgical repair of CHDs *
*Burchell et al – 1986, Ko JK et el - 1992

8. Atrio-ventricular Accessory
Pathways & the Ventricular
Pre-excitation Syndromes

10. • Understanding the variations in “Pathway –
electrophysiology – the key to understanding
variations in presentations and management issues
• Number , Location , Direction of Propagation &
Propagation velocities

11. WPW - ORT

12. Antidromic WPW

13. ORT - URAP

14. PJRT

15. Mahaim

16. WPW Syndrome

17. 1930 : Wolf, Parkinson & White described
a syndrome that consisted of
•Short PR-interval (<0.12 sec)
•Bundle branch block on surface QRS
•Paroxysmal tachycardia
1932: Wolferth and Wood – hypothesized
Extra-nodal AV connections to be the basis
for this syndrome
1969: Sealy et al surgically confirmed.
Characteristic appearance on surface ECG
during Sinus Rhythm:
Short PR interval
Slurred initial QRS ( ‘Delta wave’ ) resulting
in broadening of the QRS complex , without
widening the duration from beginning of P to
end of QRS

18. WPW Syndrome
• The most common cardiac pre-excitation syndrome.
• Overall incidence in a population study of Olmstead County,
Minnesota : 3.96/100,000 persons/year. (*Munger et al. Circ 1993)
• Exact cause unknown.
• Most cases sporadic.
• Bimodal age distribution – 1st year, then young adulthood.
• 3% of Probands have an affected 1st-deg relative.
• Familial occurrence reported – autosomal dominant inheritance.
• Recent report – Chr 7q3 in a family with WPW / HCM / HB.
• Tuberin and Hamartin gene mutations in WPW + Tuberous Sclerosis
• Myo Binding Prot / cardiac troponin gene mutations in WPW + HCM
Prevalence of WPW
In general population
0.1 – 0.3 %
In patients with CHD
0.27 – 0.86 %

19. Accessory Pathways and CHD
Uncorrected CHD in patients with
SVT
30%
70%
Infants with SVT,
with CHD
Infants with SVT,
without CHD
WPW & CHD
20-37% of infants with
WPW – uncorrected
CHD
9% of Ebsteins have
WPW
1.36% of LTGA have
WPW
1% of HOCM have
WPW
APs in CHD have a strong association with the TV
Multiple APs are common

20. Generally, AV conduction
through the accessory pathway
is faster than through the AV
Node.
Thus, some part of the
ventricle is “pre-excited” by this
eccentric spread of activation
Surface ECG in Sinus
Rhythm depends upon the
balance between ventricular
depolarization occuring through
the AV node vs the Accessory
Pathway
Greater the contribution of the
Accessory Pathway to
ventricular depolarization,
smaller the PR interval, more
prominent the Delta Wave

22. Electrophysiological characteristics
• Short or negative H-V interval on
His-Bundle electrogram
• Atrial pacing enhances pre-
excitation
• AV block results in maximum
pre-excitation
• Faster AV conduction ( Exercise
/ Isoproterenol) decreases the
pre-excitation
• Pre-excitation is lost when RR
interval shortens below the AP
effective refractory period (ERP)

23. • In WPW Syndrome, Accessory Pathways are usually
capable of conducting in both directions
• Usually the APs are “Non-decremental” in nature
• Can potentially result in several different types of
tachycardias
• Orthodromic reciprocating tachycardia (ORT) with
retrograde AP conduction is the commonest
• ORT is also commonly seen in patients without manifest
pre-excitation – “ Concealed Pathways “
• Antidromic tachycardia (ART) is seen as well, but seldom in
isolation without ORT

24. Risk of sudden death from rapid
Ventricular response to Atrial
Fibrillation

25. • Per se, WPW refers to patients with pre-
excitation in ECG + symptomatic episodes of
tachycardia – “Manifest Pathways”
• Asymptomatic patients with pre-excitation
pattern are simply described as having “VPE
pattern”
• Patients with Accessory Pathways, but no pre-
excitation are described as having “Concealed
Pathways”. Pathways may become manifest
during episodes of tachycardia

26. WPW - ORT

27. WPW - ORT

28. ORT
• The most common
manifestation of WPW in
children
• Accounting for almost
90% of SVTs
• Large peak in infancy
• Smaller peak between 6-
8 years
• Though the most
common SVT in patients
with manifest WPW, only
27-35% of patients with
ORT have pre-excitation
ORT
Others
ORT with Pre-
excitation
ORT without
Pre-excitation

29. • ORT occurs paroxysmally – with or without exercise
• Manifest as self-limited episodic palpitations with shortness of
breath, fatigue or dizziness
• Syncope is uncommon but worrisome
• Usually well tolerated
• Can cause ventricular dysfunction / hemodynamic collapse if
undetected for hours / days, especially in infants
• Faster rates (>250 BPM) and poorer condition at presentation are
seen in younger children
• Severe symptoms occur in only about 1% older children and adult
patients
ECG Features:
Narrow QRS @ 215 – 350 BPM in infants ; lower rates in older children
Tachycardia rate largely determined by AV nodal conduction
Rate-related BBB may occur especially at initiation of tachycardia ; can help
in localization of the Accessory Pathway as left / right
Retrograde ‘P’s usually occur during T-wave

30. Electrophysiological Study for confirmation of ORT
Premature ventricular beat placed when the His Bundle is refractory results in
blocking-off of the Accessory Pathway resulting in termination of the tachycardia
without atrial activation
Ventriculo-Atrial (VA) interval is prolonged by introduction of a premature VPB
when the His is refractoy
Retrograde atrial activation pattern demonstrating eccentric atrial conduction,
identically matching that during ventricular pacing
BBB during tachycardia results in persistent lengthening of the tachycardia
cycle-length
VA prolongation occurs with BBB aberration when AP is ipsilateral to the BBB

31. Initiation of Tachycardia
Critically timed Atrial premature stimulus that blocks anterograde in the
Accessory connection, and encounters an appropriate delay in AV Node
conduction so that AP and Atria are excitable when the re-entrant wave-
front reaches them
That is, at an interval < ERP of the AP
Isoproterenol
Other intiating events : High catecholamine states, exercise,
sinus acceleration, junctional beats (conducting antegrade only in
AVN) , VPBs ( conducting retrograde, only in the AP)

32. Termination of tachycardia
Spontaneous OR drug-induced block in either the AVN OR AP
OR placement of a critically timed APC that encounters AVN or AP when
they are refractory
Spontaneous termination occurs more frequently with AVN due to
increases in the vagal tone
When the last beat of the tachycardia is manifest as an atrial
stimulus without the following ventricular stimulus = Termination in the
AVN
 When the last beat of the tachycardia is manifest as a ventricular
stimulus without the following atrial stimulus = Termination in the AP

33. Electrophysiological features for differentiating ORT from AVNRT
Atrial recording ( INTRACARDIAC or ESOPHAGEAL )
ORT : VA interval > 95 milliseconds (intracardiac recording) or > 70
milliseconds ( esophageal recording) in ORT
Typical AVNRT : VA interval < 70 milliseconds by either method
{ Positive predictive value 94% ; Negative predictive value 100% ;
Sensitivity 100% ; Specificity 92% }
ORT via ‘Septal pathways’ Vs AVNRT - Para-Hissian pacing
Comparison of the VA intervals with high-output & low-output pacing
{ Hight output captures both His and the ventricle ; low output only captures
the ventricle }
Unchanged VA makes Septal pathway more likely
Premature VPB when His is refractory confirms presence of Acc Pathway

34. • Likelihood of recurrence of ORT increases with age at
presentation
• ** Data derived from studies including both treated and
untreated patients **
• Recurrence rate in ‘untreated’ patients unknown, but likely to be
higher than in treated patients
• Recurrence rates are independent of whether pre-excitation is
‘manifest’ or NOT.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Infancy 1-5 years >5 years
Risk of Recurrence
Linear (Risk of Recurrence)

35. WPW - ART

36. Antidromic WPW

37. ART
• 10% of SVTs in Adults and <
5% SVTs in children
• Rates similar to ORT but
dizziness / syncope more
common than in ORT ( due
to more uncoordinated
ventricular depolarization)
• Wide complex tachycardia
• Maximal Pre-excitation –
ventricular activation entirely
through AP
• Retrograde P-waves – axis
about -120 degrees
• Multiple APs (33%) account
for variations in patterns of
SVTs
5%
95%
ART
Others
66%
33%
Multiple APs
Single AP

38. • Requirements for occurrence of ART
– AVN anterograde conduction be blocked, while it
continues in the AP , i.e.
• Anterograde ERP of AP < ERP of AVN
• Requirements for maintenance of ART
– Retrograde RP of AVN < tachycardia cycle length
• Infrequency of both of these occurring makes it
an infrequent tachyarrhythmia

39. Electrophysiological features for differentiating ART from other Wide-
QRS tachycardias
 Regularity of ART rules out Pre-excited atrial fibrillation
 Termination of tachycardia with a VPB that does not depolarize the atria or His
rules-out Pre-excited atrial flutter and EAT
 Ventricular Tachycardia ruled out by
An Atrial premature beat that terminates the tachycardia without conducting to
the ventricle
APB can advance the tachycardia cycle-length with the SAME QRS pattern
 AVNRT with antegrade conduction down a ‘bystander’ AP ruled out by
APB that advances the tachycardia, but next atrial actrivation occurs with the
same VA interval and same retrograde atrial activation
In general, the VA interval is shorter in AVNRT

40. Immediate management of
SVT with WPW Syndrome

41. Vagal Maneuvers
Emergency
DC Version
Anti-arrhythmics
ADENOSINE
Beta Blocker
Ice pack over face
Valsalva
Carotid massage Verapamil / Digoxin
Electrophysiological
maneuvers
Esophagial pacing
Elective
DC Version
Verapamil consistently
effective but
contraindicated in infants
Both Dig & Verapamil
ABSOLUTELY
contraindicated in WPW
with Atrial fibrillation or
flutter

42. Digoxin and Verapamil can decrease the
ERP of the AP and thereby increase the
rate of conduction of Atrial impulses to
the Ventricles
Infants have under-developed
Sarcoplasmic Reticulum and may have
severe hemodynamic collapse resulting
from blocking off of the trans-membrane
Ca2+ channels by Verapamil

43. WPW with Pre-excited Atrial
Fibrillation / Flutter

44. Pre-excited Atrial Fibrillation or
Flutter in WPW
• It is the presenting symptom in 25% of older patients with WPW
• Risk of atrial fibrillation in adults with WPW – 10% to 38%
• Spontaneous Atrial fibrillation is rare in children with WPW and
even rarer in infants
• Presence of extremely rapid conducting APs in infants has
potential for disaster if atrial fibrillation DOES occur
• Can potentially result in rapid ventricular activation, even
ventricular fibrillation, depending upon conduction times and
ERPs of the AVN and the AP

45. Why does Atrial Fibrillation occur?

46. Why does the ventricular rhythm degenerate during Atrial Fibrillation ?
Multiple APs
Disorganized and
extremely irregular
Ventricular
rhythm
Activation via one AP During recovery
from activation via the other pathway
Shortened AP ERP
due to sympathetic
discharge of the
initial tachycardia

47. PRIMARY ATRIAL ACTIVITY AS A CAUSE FOR ATRIAL FIBRILLATION IN
WPW
Jais et al (Circulation 1997) suggested rapidly firing focal
atrial activity as the trigger for Atrial fibrillation in a subset of
young patients without structural heart disease
Basso et al in Circulation Jan 2001 reported the presence
of histopathological evidence of ‘focal atrial myocarditis’ in
4 of 8 (50%) patients with WPW Syndrome out of a total
series of 273 children and young adults (<35 years) who
had Sudden Cardiac Death
Lymphocytic infiltrates in 75%
Polymorphous infiltrates in 25%

48. Arrhthmogenic Atrial Myocraditis

49. Why does the ventricular rhythm degenerate during Atrial
Fibrillation ?
Atrial fibrillation
Ventricular fibrillation SCD

50. ECG features EP Factors
• Irregularly irregular
rhythm in Atrial fibrillation,
strictly regular in flutter
• Variable fusion between
AVN and AP conduction
resulting in varying QRS
morphologies
• Presence of two distinct
QRS patterns suggests
multiple APs
• EP Risk factors
• Inducible atrial fibrillation
• H/o ventricular fibrillation
• RR interval < 250ms and
antegrade AP ERP <
340ms
• In children, atrial
fibrillation may be difficult
to induce, so response of
APs to rapid atrial pacing
may suffice

51. Management
Goals
Reduce
Ventricular
Response rate
Terminate
Atrial
Fibrillation
Hemodynamics
Unstable
Relatively
stable
Synchronized
DC- Version
Procainamide

52. Long-term management
Goals
Prevent recurrence
Reduce Vent Rate
If AF recurs
Palliation –
Medical
Definitive – RFA
Medical
Palliation
Oral
Procainamide
Beta Blockade
Other Class IA,
IC
or III drugs

53. ORT without Pre-excitation – URAP
(Concealed AP)

54. ORT with Pre-
excitation
ORT without
Pre-excitation
• ORT does NOT depend upon the ability of an AP to conduct antegrade
• When ORT occurs without ventricular pre-excitation, it is said to be through
‘concealed’ or ‘unidirectional retrograde AP’ (URAP)
• Comprises nearly 60% of ORTs
• Clinical, ECG and EP manifestations identical to ORT with WPW, except for
sinus rhythm ECG
• Lacks the risk of SCD in response to atrial fibrillation

55. ORT - URAP

56. Management
• Acute management same as for ORT
• However :
– AP cannot conduct antegrade
– Lack of risk from SCD consequent to AF
– Verapamil and Digoxin are not contraindicated
– If not very symptomatic, medical management may be
preferred
• Periodic vagal maneuvers
• Digoxin / Beta blockers / Verapamil
• Class IA, IC, or III agents
– Severe or frequent symptoms – RFA is still first-line
treatment

57. PJRT

58. PJRT
• 1 – 6% of SVTs in childhood
• Rarely presents past early adolescence
• 80% present in childhood ; 50% within the first
year of life
• In the past, thought to be ‘fast-slow’ form of
AVNRT.
• Actually an ORT via an AP with decremental
conduction
• Usually, the QRS morphology is normal, both
in sinus rhythm AND during tachycardia
• Rarely, MAY be associated with antegrade
conduction and Pre-excitation in sinus rhythm

59. PJRT

60. PJRT
• Multiple APs are common
• Unlike what was previously thought, APs may be located anywhere along
the AV groove
• Results in an incessant tachycardia with relatively slow rates (150 – 250
BPM)
• During the first several years, the rate tends to slow down as a function of
delay in conduction not only in the AV node AND in the concealed
pathway.
• 50% of patients present with fatigue or even CCF
• Palpitations and syncope are unusual and occur in older patients
• May lead on to LV dysfunction

61. PJRT – EP Features
• AV node – like response to autonomic stimuli
• Long VA interval ( > 150 ms )
• Tachycardia cycle length depends upon conduction
times in the AVN and the AP
• Major contribution (nearly 64%) to the increase in cycle
lengths with age is due to the decremental retrograde
conduction across the AP
• Can be initiated / terminated with critically timed APB /
VPB

63. Distinguishing PJRT from EAT and Atypical AVNRT
• Relatively late VPC introduced during tachycardia at a
time when the His Bundle is known to be refractory will
block retrogradely in the AP & reproducibly terminate the
tachycardia, without reaching the atrium
• Not only does this preclude atrial tachycardia as a
mechanism, but if the anterograde His-Bundle potential
is also visible and therefore refractory,the VPC could not
have reached AV node.The possibility of AVNRT is ruled
out .
• As in more typical forms of AVRT, the ability to preexcite
the atria with single VPC during tachycardia at a time
when the His is refractory proves that an accessory
connection is present.

64. Management
• Emergency therapy is rarely necessary
• Maneuvers as for ORT more often turn-out to be
only diagnostic rather than therapeutic
• Therefore …………………..

65. Mahaim Pathways

66. Mahaim Tachycardia
• Mahaim fibres are long, insulated Atrioventricular
connections running between the lateral right atrium
and the anterior wall of the RV
– Most are atriofascicular rather than
nodoventricular
• Decremental conduction – usually antegrade only
• Sinus rhythm ECG shows intermittent delta wave, with
a normal PR interval
• Can support an ART using Mahaim fibres as the
antegrade limb and AVN as the retrograde limb,
resulting in a wide QRS tachycardia

67. Mahaim

68. Localization of Accessory
Pathways
Fitzpatrick et al , JACC 1994 Apr;
23(5):1272

69. AORTIC VALVE
TRICUSPID
VALVE
PULMONARY
VALVE
MITRAL
VALVE
LEFT ANTEROLATERAL
LEFT POST SEPTAL
LEFT POSTEROLATERAL
LEFT - SIDED ACCESSORY PATHWAYS
CS

71. AORTIC VALVE
TRICUSPID
VALVE
PULMONARY
VALVE
MITRAL
VALVE
RT. MIDSEPTAL
RT.ANTEROSEPTAL
RT.ANT LATERAL
RT.POST.LATERAL
RT.POST SEPTAL
RIGHT - SIDED ACCESSORY PATHWAYS
CS

73. V1 V2
V3
V4
V5
V6
I
II
III aVF
aVL
Anterior
Posterior
Right Left

74. Transition ≤ V1 ?
Yes No
Transition b/w
V1 & V2
Transition >V2
R > S by < 1.0 mv
In Lead 1
R > S by ≥ 1.0 mv
In Lead 1
LEFT SIDED
PATHWAYS
RIGHT SIDED
PATHWAYS
Sensitivity: 100%
Specificity: 97%
+ve Pred value: 98%
-ve Pred value: 100%

75. LEFT SIDED
PATHWAYS
Sum of polarities
Of Delta wave
In II, III, aVF ≥ +2
NO S > R in aVL YES
POSTERIOR
R > S in Lead 1 by > .8mv
& sum of polarities of delta
In inferior leads - Negative
NO YES
POSTEROLATERAL POSTEROSEPTAL
or
ANTEROLATERAL
V1 V2
V3
V4
V5
V6
Sen 100%
Spe 100%
PPV 100%
NPV 100%
Sen 71.4%
Spe 100%
PPV 100%
NPV 77%

76. RIGHT SIDED
PATHWAYS
Transition ≤ V3
Transition between
V3 and V4
Transition ≥ V4
SEPTAL
Delta wave in Lead II
≥ 1.0 mv
Delta wave in Lead II
≤ 1.o mv
FREE WALL
SEPTAL FREE WALL
V1 V2
V3
V4
V5
V6
Sen 97%
Spe 95%
PPV 97%
NPV 95%

77. RIGHT SEPTAL
PATHWAYS
Sum of Delta wave
Polarities in Inf
Leads ≤ -2
Sum of Delta wave
Polarities in Inf
Leads ≥ -1 ≤ +1
Sum of Delta wave
Polarites in Inf
Leads ≥ +2
POSTEROSEPTAL MIDSEPTAL ANTEROSEPTAL
V1 V2
V3
V4
V5
V6
Sen 100%
Spe 100%

78. RIGHT FREE WALL
PATHWAYS
Delta wave frontal
Axis ≥ 0 deg
Delta wave frontal
Axis < 0 deg
R wave in Lead III
> 0 mv
R wave in Lead III
<0 mv
ANTEROLATERAL
ANTEROLATERAL POSTEROLATERAL
V1 V2
V3
V4
V5
V6
Sen 87%
Spe 100%
PPV 100%
NPV 90%

89. Controversies in the long-term
management of WPW and AP-
mediated arrhythmias in children

90. Difficult RFA - technically
Asymptomatics – what to do
Lack of Pediatric data

91. Success rates
About 50%
Success rates 50%
to 96%
Blaufox. IPEJ.2005
Kugler et al. NEJM.1994

92. Risks of RFA
• Risk of complications at the time of ablation: 3.7%
• Overall risk of complications including those detected on
follow-up : 4.8%
» Kugler et al; NEJM: May 1994
Includes PE, pneumothorax, AV block, site complication
• Mortality rates : 0.12%
» Scaffer et al . AmJ Cardiol 1999

93. Risks of RFA
• Reported factors for higher risk
– Children < 1.5 Kg
– Complication rate among children < 15 Kg : 10%
• Factors favouring higher success rates
– Left sided pathways ( Rt sided are associated with higher recurrence of pre-
excitation, tachycardia, and longer flouroscopy times)
– Absence of CHD
– Better experience of the centre / operator

95. Why should we consider treating
Asymptomatic patients ?
• Life-time risk of SCD in children with WPW is 3-4%
• Young victims of SCD – 3.6% prevalence of pre-
excitation
• 0.15% to 0.39% per year over 3-10 years
• Almost 30% of initially asymptomatic individuals develop
symptoms over a 12 year follow-up period.
Munger et al. Circulation; March1993

96. How do we decide which
Asymptomatics to treat ?
Risk Stratification
Invasive Non-invasive

97. • Traditionally accepted risk factors for SCD with WPW syndrome in adults:
– H/O symptomatic tachycardia
– Shortest pre-excited RR interval < 250 ms during spontaneous or
induced AF
– Rapid ventricular response over an AP during AF (spontaneous or
induced during EPS)
– Multiple accessory pathways
– Ebsteins anomaly
– Familial WPW
These criteria have been derived mainly from studies involving adult patients –
extensively described
Not enough comparable studies in children

98. • In adults, clinical history plays an important role in
planning the management of WPW
• However, multiple studies (Deal et al, Blomberg et al,
Dubin et al) have shown that a large proportion of
children with WPW who suffered SCD had NO previous
arrhythmias / symptoms
– Deal et al : nearly 50%, Blomberg et al : 9/10 (90%)

99. • Dubin et al showed that the commonly accepted invasive criteria in
adults don’t differentiate symptomatic from asymptomatic children
with WPW
• ERPs of APs may be an invalid criterion when applied to children
• Timmerman et al associated ‘septal pathways’ to increased risk of
SCD in adults – not validated in children
• Russel et al and Blomberg et al reported left-sided pathways to be
associated with increased risk of SCD in children
• Dubin et al reported that there was no relationship between location
or number of pathways, ERPs of pathways, history of syncope, SCD
or SVT

100. • Reproducibly inducible tachycardia over
the Accessory Pathway on EP Study has
been reported to be, perhaps, the most
important factor predicting the risk of SCD
in asymptomatic children with pre-
excitation

101. • Dubin et al reported that 61% of asymptomatic
patients with WPW had inducible AVRT and 2/23
had ART ; 2/23 had ERPs <240ms
• Maybe this group of “asymptomatic” children
includes a large number who are destined to
develop symptoms by adulthood

102. • Sarubbi et al reported inducible SVT in 49% of
asymptomatic patients with pre-excitation who
underwent EPS
• In 25%, SVT was initiated after Isoproterenol
infusion – arguing for the need for aggressive
induction protocols
• No relation to age , sex , pathway localization
B.Sarubbi et al, Heart 2003;89

103. • Pappone et al (NEJM.2004) in their study of 165 asymptomatic children between 5-12 years
age with WPW did EP Study for all
• ‘High risk’ group for arrhythmic events on follow-up was defined as those with reproducibly
induced AVRT / AF
• ‘High risk’ patients were randomized and into ablation and non-ablation groups
• Over 34 months follow-up, only one event (SVT) was reported in the ablated group.
• But 44% of the non-ablated group developed ‘life-threatening’ arrhythmias over a median 19
months follow-up
• In addition, 5 more patients in the non-ablated group, though asymptomatic, showed ‘silent
AF’ on follow-up Holter monitoring, of whom one patient had a sudden death, one had pre-
excited AF and one presented with VF. All these 3 had multiple pathways and had inducible
AVRT and AF
• Of the ‘Low risk’ group, on 34 months median follow-up, 8% had an arrhythmic event
• Recommendation : Children with reproducible induction of AVRT or sustained AF (>30 sec) or
both should undergo detailed mapping and prophylactic RFA
• Risk of EP Study – 3% risk of complication due to EPS, 3% related to anaesthesia

104. EPS & RFA

105. Thank You
** YAWNNNNN**