9/8/2012 1 Utility of cardiac MRI for identifying the Arrhythmia Substrate during VT ablation Timm Dickfeld, MD, PhD Director of Electrophysiology, VA Baltimore Associate Professor of Medicine, University of Maryland MACIG (Maryland Arrhythmia and Cardiac Imaging Group) www.umm.edu/heart/macig Disclosure-of-Relationship - Research Grants, Consulting – Biosense-Webster Unlabeled Indications - Use of Gadolinium for MRI Scar Imaging Why Substrate Characterization? 4.3g myocardium = 1.4% LV mass • In 193 patients LGE of 1.4% resulted in HR >7 for MACE Kwong R. et al. Circulation. 2006;113:2733 Anatomic Substrate of Reentrant Arrhythmias De Bakker et al. Circulation 1988 Adapted: Stevenson W. Circulation. 1993;88:1647 Inner Loop Outer Loop Bystander Exit Isthmus Entry
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9/8/2012
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Utility of cardiac MRI for identifying the Arrhythmia Substrate during VT ablation
Timm Dickfeld, MD, PhDDirector of Electrophysiology, VA Baltimore
Associate Professor of Medicine, University of MarylandMACIG (Maryland Arrhythmia and Cardiac Imaging Group)
www.umm.edu/heart/macig
Disclosure-of-Relationship
- Research Grants, Consulting –Biosense-Webster
Unlabeled Indications
- Use of Gadolinium for MRI Scar Imaging
Why Substrate Characterization?
4.3g myocardium = 1.4% LV mass
• In 193 patients LGE of 1.4% resulted in HR >7 for MACE Kwong R. et al. Circulation. 2006;113:2733
Anatomic Substrate of Reentrant Arrhythmias
De Bakker et al. Circulation 1988 Adapted: Stevenson W. Circulation. 1993;88:1647
Wijnmaalen et al. . Eur Heart J. 2011;32:104Desjardins et al. Heart Rhythm 2009;6:644
Dickfeld et al. Circ Arrhythm Electrophysiol. 2011;4:172
Perez-David E et al. J Am Coll Cardiol 2011;57:184Gupta et al. JACC CV Imaging. 2012;5:207
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VT Case #1• 76 yo pt with PHM of HTN, DM, new recurrent
VT on Amio, CC in OSH: no CAD, EF 35%
LBRI axisCL 420ms
Transition V4, no notching V1/2, QRS onset-nadir V1 <90msWinjmaalen et al. Circ Arrhythm Electrophysiol. 2011;4:486
VT Case #1
12/12 PM
NS VT inducible with burst pacing and PES (2ES)
VT Case #1
What is the VT mechanism?
R ee n t
r a nt V T
A ut o m
a t i c/ t r i
g . . .
D on ’ t
k n ow
27%30%
43%
1. Reentrant VT
2. Automatic/triggered VT
3. Don’t know
Ablation Lesion extending into Scar Substrate
MRI-Guided Ablation: Scar + Ablation
Pre-RFA
PostRFA
Tian et al. Circ Arrhythm Electrophysiol. 2012.1;5(2):epub31
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• Further refinement of binary concept (DE+/-)• Introduction of MRI scar core and periphery• Analogous to voltage-defined border zone
De Bakker JM. Circ Arrhythm Electrophysiol 2010; 3:204
‘Grey Zone’- Mixture of Scar and Normal Myocardium -
Schmidt A et al. Circulation. 2007;115:2006
• Grey zone correlated in ischemic patients with all-cause mortality, inducibility of MMVT and appropriate ICD shocks
• Three different definitions:- Scar (>3SD), Grey Zone (2-3 SD), - Scar (>50% max SI), Grey Zone(>peak remote/<50%max SI)- Scar (>50% max SI), Grey Zone (35-50% max SI)
‘Grey Zone’- Mixture of Scar and Normal Myocardium -
Yan A. et al. Circulation 2006;114;32
Roes S. Circ Cardiovasc Imaging. 2009;2:183
• Ischemic swine model (n=17)
• Inducible VT correlated with larger grey zone (25±10% vs. 13±5%)
• Successful RFA of 22 VT, at least one lesion in grey zone
• Residual inducibility found with preserved grey zone
‘Grey Zone’- Mixture of Scar and Normal Myocardium -
Esthner H. Heart Rhythm 2011, doi: 10.1016
Grey Zone – Human Studies
• 18 patients with ischemic CMP and MMVT compared with 18 matched patients
• Scar core (>3SD) and Grey zone (2-3SD)• Continuous grey zone corridors (88% vs. 33%,
p<0.001)• Voltage-map channels corresponded to Grey
zone channels
Perez-David E et al. J Am Coll Cardiol 2011;57:184
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Grey Zone – Human Studies
• 10 patients with ischemic CMP and VT RFA• Voltage as gold standard• Best MRI match with FWHM 60% and
subendocardial half-wall thickness (scar r2=0.808; p<0.001 and BZ: r2=0.485; p=0.025)
• Identified 81% of voltage-defined channels
Andreu D. et al. Circ Arrhythm Electrophysiol. 2011;4:674