Background The aim of this study was to clarify the electrocardiographic characteristics of repetitive monomorphic ventricular tachycardia (RMVT) originating from the left ventricular outflow tract, and to describe the results of treatment with radiofrequency catheter ablation (RFCA).Methods Routine 12-lead surface electrocardiography and electrophysiological studies were performed on 11 RMVT patients with no organic heart disease, who were subsequently treated with RFCA directed at targets identified by pace mapping.Results The surface electrocardiogram QRS characteristics of RMVT included an atypical left bundle branch block and right axis deviation, with a low amplitude “rs” or “rS” pattern in lead I , an “rS” or “RS” pattern in V1, and a precordial R wave transition zone in V2 or V3. In 1 patient, a small S wave was observed in V5. Using pace mapping techniques, we selected the left coronary cusp as the ablation target. RMVT was eliminated in all 11 patients immediately after radiofrequency energy d Background The aim of this study was to clarify the electrocardiographic characteristics of repetitive monomorphic ventricular tachycardia (RMVT) originating from the left ventricular outflow tract, and to describe the results of treatment with radiofrequency catheter ablation (RFCA). Methods Routine 12-lead surface electrocardiography and electrophysiological studies were performed on 11 RMVT patients with no organic heart disease, who were succeeded treated with RFCA directed at targets identified by pace mapping. Results of the surface electrocardiogram QRS characteristics of RMVT included an atypical left bundle branch block and right axis deviation, with a low amplitude “rs ” or “rS ” pattern in lead I, an “rS ” or “RS ” pattern in V1, and a precordial R wave transition zone in V2 or V3. , a small S wave was observed in V5. Using pace mapping techniques, we selected the left coronary cusp as the ablation target. RMVT was eliminated in all 11 patients immediately aft er radiofrequency energy d