Distribution of Successful Ablation Sites of Idiopathic Right Ventricular Outflow Tract Tachycardia

Abstract

There are few studies evaluating the distribution of successful ablation sites of idiopathic right ventricular outflow tract (RVOT) arrhythmias using a three-dimensional electroanatomical mapping system. This study aims to clarify the favorite site of idiopathic RVOT arrhythmias through electroanatomical voltage mapping using the CARTO system (Biosense Webster, Diamond Bar, CA, USA). A consecutive series of 72 patients (mean age 43.6 +/- 16.2 years, 32 males) who underwent radiofrequency catheter ablation (RFCA) for a total of 82 morphologies of idiopathic RVOT arrhythmias were studied. Detailed three-dimensional electroanatomical voltage maps of the RVOT were obtained using the CARTO system prior to the RFCA during sinus rhythm. The voltage on bipolar electrogram was defined as follows: amplitude < 0.5 mV as "low-voltage zone," amplitude between 0.5 and 1.5 mV as "transitional-voltage zone," and amplitude >1.5 mV as "high-voltage zone." Successful ablation sites were electroanatomically classified into each voltage zone. Successful ablation was acquired in 63 patients and 71 RVOT arrhythmias (63/72 patients: 87.5%, 71/82 RVOT arrhythmias: 86.5%). In the successful group, three arrhythmias (4.2%) were classified in the low-voltage zone, 63 arrhythmias (88.7%) in the transitional-voltage zone, and five arrhythmias (7.0%) in the high-voltage zone. This study indicates that the vast majority of successful ablation sites for idiopathic RVOT arrhythmias are located in the transitional-voltage zone. Mapping of the transitional-voltage zone may be an important landmark of RFCA for RVOT arrhythmia.