Right Ventricular Radiofrequency Ablation of Ventricular Tachycardia After Myocardial Infarction VOLKER MENZ, VUONG DUTHINH, DAVID J. CALLANS, DAVID SCHWARTZMAN, CHARLES D. GOTTLIEB, and FRANCIS E. MARCHLINSKI From the Philadelphia Heart Institute, Presbyterian Medical Center, Philadelphia, Pennsylvania MENZ, V., ET AL.: Radiofrequency Current Ablation of Ventricular Tachycardia After Myocardial In- farction. Radiofrequency transcatheler ablation of ventricular tachycardia in the setting of a prior my- ocardial infarction is typically performed with application of energy to the left ventricular endocardium. In this article, two cases are descnbed in which successful radiofrequency transcatheter ablation of ven- tricular tachycardia occurred with energy delivery to the right ventricular septum after failed ablation at- tempts from the left ventricle. Both patients had tachycardias with a left bundle branch block morphology and markedly presystolic activity recorded from the right ventricular septum. Right ventricular septa! ac- tivation mapping during ventricular tachycardia should be performed in patients with left bundle branch block tachycardia morphology and coronary artery disease to maximize efficacy of the catheter ablation procedure. (PACE 1997; 20:1727-1731} ventricular arrhythmias, catheter ablation Introduction Radiofrequency current ablation of ventricu- lar tacbycardia (VT) has been shown to be effec- tive in selected patients. Rates of success in pa- tients with coronary artery disease (CAD) vary between 17% and 75%.^~^ The basis for the lack of a more uniform success rate has not heen deter- mined. In previous reports, radiofrequency energy has been applied to the left ventricular endo- cardium in patients with VT in the setting of CAD. In this article, we document a right ventricular "site of origin" in two patients with VT occurring after remote myocardial infarction (MI). In hoth patients very early presystolic activity was only recorded from the right ventricular septum. At- tempts to ablate the VT with radiofrequency en- ergy applied in the left ventricle to sites demon- strating only minimal presystolic activation failed. Radiofrequency current application to the Supported by the Sidney Kimmul Research Foundation. Dr. Volker Menz is supported hy a grant from the Deutsche Forschungsgemeinschaft in Bonn, Germany. Address for reprints; Francis E. Marchlinski. M.D., Allegheny University Hospital. Electrophysiology Section. Broad and Vine Streets. Mail Stop 471. Philadelphia, PA Fax: (215) 991- 4881, site of early presystolic activity more than 100 ms before the onset of the surface QRS complex in the right ventricle terminated the tachycardia and pre- vented reinitiation. Case Reports The first patient is a 76-year-old woman with a history of inferior wall MI 1 year prior to pre- sentation. She had been admitted repeatedly to another hospital for wide complex tachycardia, which was tolerated hemodynamically but ac- companied by sustained palpitations. The 12-lead ECG revealed a leftward and superior frontal- plane axis and a left bundle branch block mor- phology with a cycle length of 390 ms (Fig. la). The arrhythmia recurred during empiric treat- ment with procainamide. Cardiac catheterization demonstrated a totally occluded right coronary artery that was filled left-to-right via collaterals with only luminal irregularities in the other major vessels. The left ventricular ejection fraction de- termined from a right anterior oblique (RAO) ven- triculogram was 40%. The inferolateral wall was hypokinetic. The patient was transferred to our in- stitution for catheter ablation of the ventricular ar- rhythmia. PACE, Vol. 20 June 1997 1727