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DEBATE

Asymptomatic Subjects with WPW Pattern Should Undergo

Catheter Ablation

Edmund Keung, MD Chief, Clinical Cardiology

San Francisco VAMC October 23, 2010

DEBATE

Asymptomatic Subjects with WPW Pattern Should Undergo

Catheter Ablation

Disclosure •  The speaker

–  Does not serve on any industry advisory or consultation board

–  Does not receive any grants from industry

–  Is not a member of any speakers’ bureau

–  Is poor

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Aftermath of Last Year’s Debate

DEBATE

Asymptomatic Subjects with WPW Pattern Should Undergo

Catheter Ablation

My Concession Presentation

On Wolff-Parkinson-White Pattern and Syndrome

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Intracardiac tracings show the normal intervals between

• initiation of atrial depolarization A

• His bundle activation H • ventricular depolarization V • AH + HV = PR interval

Normal Sinus Rhythm

ECG requirements for diagnosis of WPW pattern

• P-R interval < 120 ms • Normal P wave vector (to exclude junctional rhythm)

• Presence of a delta wave • QRS duration > 100 ms

AV Conduction using an Accessory Pathway (Bypass Track)

WPW Pattern versus Syndrome

•  Pre-excitation (delta waves) on 12-lead ECG = WPW ECG pattern

•  Pre-excitation + symptomatic arrhythmias* = WPW syndrome

*Most common types: AVRT, AF

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Wolff-Parkinson-White Pattern Left anterolateral accessory pathway

• Can be initiated by a closely coupled premature atrial complex (PAC)

• Blocks in the accessory pathway

• But conducts through the AV node

• Retrograde conduction via accessory pathway

• inverted P wave produced by retrograde conduction visible in the inferior ECG leads

WPW Syndrome – AV Re-entrant Tachycardia, Orthodromic

WPW Syndrome – AV Re-entrant Tachycardia, Orthodromic

•  Narrow QRS tachycardia – using normal AVN-Purkinje fiber for antegrade AP for retrograde conduction

•  Short RP tachycardia

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Accessory Pathway Manifest versus Concealed

•  Pre-excitation (delta waves) on 12-lead ECG = manifest

•  Only capable of retrograde conduction (never demonstrate delta waves) = concealed

WPW Pattern Epidemiology

•  Prevalence of a WPW pattern on 12-lead ECG in the general population: 0.15 - 0.25% (or 1.5 to 2.5/1000)

•  Yearly incidence of newly diagnosed cases of WPW: 0.004% (4 per 100,000)

•  50% of the newly diagnosed cases were asymptomatic

WPW Pattern Epidemiology

•  WPW pattern on the ECG may be intermittent

•  Up to 40% of cases pre-excitation disappear permanently – Pre-excitation disappears in older

patients (>= 50 years of age)

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•  Prevalence is much lower than that of WPW ECG pattern

•  Among 25,000 healthy aviators –  0.25% (63) showed WPW ECG pattern –  1.8% out of 63 (1) had documented arrhythmia

WPW Syndrome Epidemiology

•  Occurrence of arrhythmias is related to the age at the time pre-excitation is discovered

•  1/3 of asymptomatic patients age < 40 eventually developed symptoms

•  None among age > 40

WPW Syndrome Epidemiology

•  AF develops spontaneously or AVRT degenerates to AF

•  AF can be life-threatening if the bypass tract has a short antegrade effective refractory period (able to conduct fast to the ventricle)

•  Very fast ventricular rate (>300 bpm) can result in deterioration into VF and SCD

WPW and Sudden Cardiac Death (SCD) The Culprit - AF

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WPW- AF with Rapid Ventricular Response

Principal Argument for Catheter Ablation for asymptomatic WPW

Pattern

•  To prevent sudden cardiac death •  Not to prevent future development of

arrhythmias –  Abundant opportunity to direct curative

treatment for those who develop arrhythmias later

•  Incidence of SCD with WPW syndrome: – 0.15% to 0.39% over a 3- to 10-year

follow-up •  Unusual for cardiac arrest (VF) to be the

first symptomatic manifestation of WPW syndrome

•  Rare over age 30

Sudden Cardiac Death (SCD) Rarely Occurs in WPW

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Incidence of SCD

Authors n EPS SCD Follow-up (yrs)

Klein 29 yes 0 4.5

Satoh 34 yes 0 1.3

Beckman 15 yes 0 7.5

Leitch 75 yes 0 4.3

Fukatani 64 yes 0 6.6

Brembilla-Perrot 40 yes 0 1.8

Berkman 128 no 0 18

Soria 78 no 2 5.7

Munger 53 no 0 10.1

Goudevenos 77 no 0 4.6

Fitzsimmons 187 no 0 21.8

2 out of 780 patients (0.25%)

Todd, Klein, Krah, et al. JACC 2003;41:245

A Study of Interest Usefulness of Invasive EP Testing to Stratify the Risk of

Arrhythmic Events in Asymptomatic Patients with WPW Pattern*

•  EP studies in 212 asymptomatic WPW patients •  50 excluded in the final analysis •  Mean follow-up: 37.7 mos •  33/162 (20.4%) became symptomatic

–  29/33 (88%) had inducible AVRT –  11/29 AVRT →  AF  

•  Only 4/115 non-inducible patients developed SVT •  3 VF (1 died) – 1.4%

*Pappone, Sentinelli, Rosanio al. JACC 2003;41:239

Factors associated with development of VF

•  Multiple AP present in the 3 patients with VF

•  Had both inducible AVRT and AF and documented spontaneous AF during follow-up

•  A short antegrade ERP

*Pappone, Sentinelli, Rosanio al. JACC 2003;41:239

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Counter-Points

•  All 3 VF patients developed symptomatic AF before the events

•  Strategy of EP testing and ablate only when symptoms develop: – No patient would die – Only 33 patients would have been ablated – 129 patients would have been spared an EPS

and its complications

Todd, Klein, Krah, et al. JACC 2003;41:245

Complications of RF Ablation Studies n Comp

Rate Perforation/tamponade

Complete AV block

MI CVA Death

MERFS 2,222 98 (4.4%)

16 (0.72%)

14 (0.63%)

0 11 (0.49%)

3 (0.13%)

NASPE 5,427 99 (1.8%)

7 (0.13%)

9 (0.17%)

3 (0.06%)

8 (0.15%)

4 (0.07%)

Atakr 500 NA NA 5 (1%)

NA 1 (0.2%)

1 (0.2%)

•  Overall Complication rate of 2.5% •  Risk and success rate varies with pathway location

−  Left-sided AP – risks of trans-septal puncture or retrograde aortic approach

−  Septal AP – risks of complete heart block and pacemaker for life

MERFS: Multicenter European Radiofrequency Survey (MERFS), 1993 North American Society of Pacing and Electrophysiology (NASPE), 1993 Atakr Multicenter Investigator Group, 1999

Todd, Klein, Krah, et al. JACC 2003;41:245

•  EP study in an asymptomatic WPW patient will invariably leads to RF ablation

•  2.5% complication rate of RF ablation is significant to an asymptomatic, young patient

•  Physicians shall do no harm in treating asymptomatic patients

More Counter-Points

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•  Experts know best – Let us visit the clinical guidelines

Management of Asymptomatic Patients with WPW Pattern

Management of Asymptomatic Patients with WPW Pattern

Circulation 2003;108:1871

•  20% of asymptomatic patients demonstrates a rapid ventricular response during induction of AF in EP studies

•  During follow-up, very few patients developed symptomatic arrhythmias

•  Even less had cardiac arrest (0.25 – 1.4%) •  Positive predictive value of EPS is too low to

justify its routine use in asymptomatic patients

Teaching According to Mel

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ACC/AHA/ESC Practice Guidelines

Recommendation Classification Level of Evidence

Pre-excitation, asymptomatic

None I C

Catheter ablation IIa B

Class I: There is evidence for and/or general agreement that the treatment is useful and effective Class IIa: There is a conflicting evidence and/or opinion about the usefulness of the treatment. The weight of evidence/opinion is in favor of the treatment Evidence B: Data are from a limited number of randomized trials, nonrandomized studies or observational registries Evidence C: Expert consensus

My Last Words, I Think

•  Well-informed patients and parents •  Small risk over a long period of time •  A one-time risk over a short span

(ablation) •  Athletes and higher risk occupations •  Age > 30 yr have extremely low risk

of SCD

Congratulations, Ronn

2009 2010

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The Giants game is at 4:30 PM

Non-Invasive Markers for Low Risks

•  Low sensitivity and specificity •  Intermittent loss of pre-excitation

(longer AP effective refractory period)

•  Sudden loss of pre-excitation during exercise (longer AP ERP)

•  Loss of pre-excitation after antiarrhythmic treatment

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Invasive EP Study – Low Specificity

•  An SPPR (Shortest Pre-exciting RR interval of <250 ms (240 bpm) is sensitive but not specific marker of risk of VF

•  30% of asymptomatic WPW will have an SPRR <250 ms during induced VF

Left anteral Lateral AP