Catheter Ablation of Left Ventricular Summit Arrhythmia in a Patient with Critical Coronary Artery Stenosis: A Sequential Approach

The left ventricular (LV) summit is the usual source of epicardial idiopathic premature ventricular contractions (PVCs). A 56-year-old male patient presented to the cardiology outpatient clinic with palpitations and dyspnea. Twelve-lead electrocardiography performed on admission revealed monomorphic PVCs with precordial QRS transition in the V1 derivation and an rS pattern in the D1 derivation and inferior axis. An electrophysiology study and ablation procedure were planned. Activation mapping guided by a three-dimensional electroanatomic system was conducted to identify the earliest site of ventricular activation of the PVCs. During the PVCs, the earliest ventricular activation was observed within the great cardiac vein (GCV) and preceded the QRS onset by 37 ms. Coronary angiography was performed before ablation in the coronary venous system (CVS) to assess the distance from the coronary artery, which showed severe stenosis in the left circumflex artery. Then, percutaneous coronary intervention was performed to address the left circumflex artery stenosis. Anatomic catheter ablation was performed in the aortic cusp and endocardial LV outflow tract, the sites adjacent to the LV-summit PVC origin. However, successful ablation could not be achieved. Subsequently, an irrigated radiofrequency current was delivered in the GCV for 60 seconds, with the power being gradually increased to 30 W and with an irrigation flow rate of 30 mL/min. After ablation, under isoproterenol infusion and burst pacing from the right ventricle, no PVC or ventricular tachycardia was observed. Special precautions should be taken to avoid coronary artery damage during ablation from distal CVS. This approach may increase the success of ablation and avoid potential complications.