Cardiac Resynchronization Debate: Narrow QRS

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Cardiac Resynchronization Debate Narrow QRS

• Cecilia Fantoni, MD
• Department of Cardiology
• Otto-von-Guericke Universität
• Magdeburg, Germany

Genova, 1st April 2005
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Narrow vs Long QRS Pts
NYHA III/IV
LVEF
Plt0,01
Plt0,004
LVEDV
MR 3/4
Plt0,001
Plt0,001
Ghio et al, EHJ 200425571
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Narrow vs Long QRS Pts
Gottipaty et al. JACC 1999 33(2)145A
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Narrow QRS PtsLess Sick, Better Left Ventricle
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Long QRS What we know
All Randomised Controlled Trials
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Narrow QRS What we know
All Observational Studies
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Narrow QRS (lt120ms)Intra-LV Mechanical
Dyssynchrony
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Systolic Mechanical Dyssynchrony
Intra-ventricular
Inter-ventricular
Careful Pts screening
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Narrow QRS PtsLow Prevalence of Mechanical
Dyssynchrony
Careful Pts screening
Uniform Criteria
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Diastolic dyssynchrony
Normal
lt120 ms
gt120 ms
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Yu et al. Heart 20038954
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Narrow QRS Diastolic dyssynchrony
Turner et al. Heart 200490502
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Most delayed segments
Pacing site??
Ghio et al, EHJ 200425571
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Why does it work ?
?
Mechanical Dyssynchrony
Electrical Therapy
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Mechanical Dysfunction due to Electrical
Disturbance
LATERAL WALL
SEPTUM
Electrical activation
Mechanical activation
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HF Pts Activation Pattern
All Idiopathic Dilated Cardiomyopathy
Normal QRS morphology
Left Bundle Branch Block
98 msec
125 msec
166 msec
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Intra-Mural Electrical Delay
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Intra-Mural Electrical Delay
CONTACT (Carto)
NON CONTACT (EnSite)
BIPOLAR
UNIPOLAR
ENDOCARDIUM
TRANSMURAL
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LBBB Multilayer disease?

• Left ventricular enlargment

Disarray of myocardial layers
Anisotropic conduction
Intra-mural conduction delay
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Narrow QRS PtsNormal Activation TimesNormal
Activation Pattern
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Absence of Electrical Abnormality in Presence of
Mechanical Dyssynchrony

• Incomplete Understanding of Pathophysiological
  Mechanism
• Electro-Mechanical Mismatch
• Jeopardized Myocardium Scars
• Silent Ischemia
• Regional Increase Wall Strain
• Deposition of Extra-cellular Matrix
• Mitochondrial Alteration
• Ca Metabolism Changes

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Issues in Narrow QRS

• Narrow QRS
• Less Sick Patients
• Less Compromised Heart
• Non Uniform Criteria of Mechanical Dyssynchrony
• Pacing Site
• Systolic vs Diastolic Dyssynchrony
• Observational Studies
• Small No. Pts Included
• Short-term Follow-up

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CRT Implantation in PTS with QRS lt120 ms?
YES
NO
Not Biased View
Biased View
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Predictors of Intra-LV mechanical Dyssynchrony
R0,56 plt0,0001
R0,57 plt0,0001
Intra-LV Dyssynchrony
Inter-V Dyssynchrony
QRS
QRS
Fauchier et al, AJC 200392341
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Myocardial Fibers of the Normal Heart