Idiopathic Ventricular Arrhythmia Originating From the Cardiac Crux or Inferior Septum Epicardial Idiopathic Ventricular Arrhythmia

Background-Idiopathic ventricular arrhythmia (VA) can arise from the epicardium near the posteroseptal region (cardiac crux). There are only 2 prior reports describing idiopathic VA from the cardiac crux. The purpose of this study was to characterize the clinical and the electrocardiographic features of idiopathic crux VA. Methods and Results-Crux VA was identified in 18 patients undergoing catheter ablation. We divided patients into 2 groups, those with VA originating from the apical crux (n=9) and the basal crux (n=9). We described the clinical and electrocardiographic characteristics of crux VA as well as the ablation results. Furthermore, we compared clinical features of crux VA with other sites of idiopathic VA. Fifteen crux VA patients (83%) had sustained ventricular tachycardia and 3 patients required implantable cardioverter defibrillator implantation because of syncope. All patients had a left superior axis and 16 patients had R>S wave in V2.In apical crux VA, all patients had a deep S wave in V6 and 8 patients (89%) had R>S wave in aVR. All apical crux patients underwent attempted ablation in the middle cardiac vein without success. In 4 of these patients, epicardial ablation with subxiphoid approach was performed successfully. All basal crux VA patients had either negative or isoelectric pattern in V1 and had R>S in V6. Patients had successful ablation within the middle cardiac vein. Conclusions-Apical versus basal crux VA is identified as a new category of idiopathic VA with distinctive electrocardiographic characteristics; ablation via the middle cardiac vein is effective for eliminating basal crux VA, whereas apical crux VA often requires a subxiphoid epicardial approach.