Anti-arrhythmic Medication v. MRI-Merge Ablation in the Treatment of Ventricular Tachycardia
Status:
Withdrawn
Trial end date:
2015-08-01
Target enrollment:
Participant gender:
Summary
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.