Endocardial, epicardial, and right atrial approach for catheter ablation of premature ventricular contractions from the inferoseptal process of the left ventricle

BACKGROUND: Inferoseptal process of the left ventricle (ISP‐LV) might be a source of idiopathic ventricular arrhythmias. In these cases, ectopic foci are accessible from the LV endocardium, epicardially from the middle cardiac vein as well as from the right atrium (RA). This study reports a series of patients with premature ventricular contractions (PVCs) arising from the ISP‐LV that were successfully ablated following access from different structures. METHODS AND RESULTS: Five patients (4 males, age 61 ± 12.8 years) with PVCs arising from the ISP‐LV were successfully ablated using three different approaches for ablation—endocardial, epicardial (through coronary sinus or its branches), and RA approaches. Endocardial LV mapping, RA, and coronary sinus (CS) mapping were performed in all five cases. PVCs demonstrated RBBB or LBBB‐like morphology and left superior axis. The three patients ablated endocardially had a maximum deflection index (MDI) of 0.36, 0.43, and 0.54, whereas in the remaining 2 patients, MDI was 0.57 and both demonstrated QS morphology in the inferior leads. Local activation time at the successful ablation site was 35 ± 8.9 (26–55) msec pre‐QRS. Pacemapping at the successful ablation site resulted in a good (11/12) or perfect (12/12) QRS match in all cases. Three of the patients demonstrated frequent monomorphic PVCs of another morphology suggesting a remote exit site. All patients remained arrhythmia‐free after a mean follow‐up of 21 ± 15 (6–36) months. CONCLUSION: Successful ablation of PVCs from ISP‐LV may require access from the CS or even RA apart from LV endocardial approach. Not infrequently patients demonstrate additional PVC foci.