Epicardial ablation of ventricular tachycardia using a new high-density mapping system.

We report the case of a 44-year-old woman who was referred for ablation of recurrent ventricular tachycardia (VT) in the setting of dilated cardiomyopathy secondary to myocarditis. The ECG displayed a right bundle branch block morphology and superior axis in the frontal plane, associated with a pseudo delta wave in the precordial leads that suggested an epicardial origin. Cardiac magnetic resonance performed prior to the procedure showed late gadolinium enhancement at the lateral wall of the left ventricle (LV) and excluded subendocardial fibrosis in either ventricle. This information was crucial and influenced the ablation strategy, identifying the target area as exclusively epicardial, thus avoiding unnecessary mapping of the endocardial surface of the LV. Epicardial activation mapping and ablation during VT were performed using the Orion® high-density catheter (Boston Scientific Inc.) and the Rhythmia® mapping system (Boston Scientific Inc.). Applications near the exit site immediately terminated the tachycardia, which was no longer inducible. One year after the procedure the patient was still in sinus rhythm with no episodes of VT or non-sustained VT recorded by continuous monitoring via an implanted cardioverter-defibrillator.