Anti-arrhythmic Medication v. MRI-Merge Ablation in the Treatment of Ventricular Tachycardia
Anti-arrhythmic Medication v. MRI-Merge Ablation in the Treatment of Ventricular Tachycardia
Ventricular tachycardia (VT) is a morbid arrhythmia responsible for many sudden deaths and
 ICD shocks. Despite much progress in the treatment of arrhythmia, VT remains a therapeutic
 challenge. Most patients with VT have an implantable cardioverter defibrillator (ICD) for
 secondary prevention of sudden cardiac death, however, an ICD merely treats VT, it does not
 prevent VT. In patients with recurrent VT and ICD shocks, two strategies are available to
 decrease the burden of VT. The first is antiarrhythmic drugs, and the second is VT ablation.
 The aim of this study is to compare the efficacy of antiarrhythmic drugs and VT ablation
 guided by MRI. VT can sometimes be suppressed with antiarrhythmic medications, however, these
 are often ineffective, and carry a high burden of side effects. Many forms of VT can be cured
 by selective destruction of critical electrical pathways with catheter ablation. A major
 limitation in the ablation of VT, however, is the time required to localize scar tissue and
 important pathways for targeting of lesions. Magnetic resonance imaging can now obtain
 reliable images of scar location within the ventricles. Recent advances in electroanatomical
 mapping systems allow operators to import pre-acquired images into the mapping system. The
 aim of this study is to examine the feasibility of importing historic MRI scar maps of the
 ventricles into the electroanatomical system and using such images to guide catheter
 ablation, as compared to antiarrhythmic drug suppression of VT. We suspect that MRI guidance
 will be especially useful in patients with "unstable" VT, i.e. VT that causes an abrupt drop
 in blood pressure, and thus cannot be maintained in the electrophysiology (EP) lab for
 mapping and entertainment purposes. Patients referred for VT ablation have ICDs. Through
 previously completed animal work (Circulation 2004; 110(5): 475-82) and a human trial (2006
 Sep 19;114(12):1277-84) we have demonstrated the safety of MRI in the setting of pacemakers
 and implantable defibrillators using appropriate precautions. Through careful device
 programming and using MRI sequences with limited energy exposure (specific absorption rate <
 2 W/kg) we will study the pre procedural myocardial anatomy of patients enrolled into this
 study.

 The primary endpoint will be lack of VT documented by implantable defibrillator (when
 present) interrogation or Holter monitoring 6 months post ablation. The secondary endpoints
 will be comparison of inducible arrhythmia at the end of the procedure, procedure time,
 comparison of endocardial voltage mapping to scar on delayed enhancement MRI images, and
 complications in each study arm.
Inclusion:

 -  Current treatment with amiodarone

 -  Ischemic or non-ischemic cardiomyopathy

 -  Monomorphic ventricular tachycardia at any cycle length, with > 1 occurrence of the
 same cycle length and morphology, at least one episode needs to be of sufficient
 duration to result in a shock.

 -  No contraindication to up titration of meds or to VT radiofrequency ablation (RFA)

 Exclusion:

 -  Primary antiarrhythmic medication other than amiodarone

 -  Amiodarone at dose of 600 mg daily or higher

 -  Polymorphic VT as culprit rhythm

 -  History of metal exposure (welding)

 -  Pregnant women

 -  Recent myocardial infarction

 -  Planned coronary revascularization

 -  Implantable cardiac devices not previously tested for safety in the setting of MRI

 -  Glomerular Filtration Rate (GFR) < 30 ml/min