Idiopathic ventricular arrhythmias arising from the left ventricular outflow tract: Tips and tricks

Idiopathic left ventricular outflow tract ventricular arrhythmias (LVOT-VAs) arising from the LVOT are rare compared with the VAs arising from the RVOT. Idiopathic LVOT-VAs have been divided into four subgroups based on successful catheter ablation sites: the aorto-mitral continuity (AMC), the anterior site around the mitral annulus (MA), the aortic sinus cusps (ASC), and the epicardium. Recognition of the ECG characteristics of LVOT-VAs combined with anatomical information should facilitate their appropriate diagnosis and treatment. In particular, the AMC is located adjacent to the anterior site of the MA, ASC, and epicardium. All subtypes of LVOT-VAs, except those with epicardial origins, are successfully treated with endocardial radiofrequency catheter ablation combined with pace mapping and the identification of the earliest ventricular electrogram with a prepotential, if it is recordable. In addition, LVOT-VAs originating from an inaccessible area in the LV summit of the epicardium, which cannot be treated by epicardial catheter ablation, should be differentiated from those in an accessible area using novel electrophysiological characteristics. Despite many morphological similarities among the subtypes of LVOT-VAs, the ECG characteristics and anatomical information obtained from visualization using computed tomographic image integration with electroanatomical mapping may advance the safety and success of catheter ablation of idiopathic LVOT-VAs.