Case report
A 73-year-old man was referred to our hospital for ablation of a symptomatic persistent AT. Nine years ago, the patient underwent surgery for coronary artery bypass grafting and aortic valve replacement. During this surgical procedure, the patient additionally received ablation treatment performed with HIFU (Epicor™, St Jude Medical, Maple Grove, MN) due to paroxysmal AF. At presentation, a dilated left ventricle with moderately reduced left-ventricular ejection fraction of 32% and a left atrial volume of 77 ml with only mild mitral regurgitation was detected. The biological aortic valve prosthesis was in proper location and well-functioning with a mean aortic valve pressure gradient of 21 mmHg.
During the electrophysiological procedure, a 7 French (F) 10-pole deflectable catheter was placed into the coronary sinus (CS) via femoral venous approach, which confirmed the left-atrial AT with a cycle length (CL) of 280ms and a 2:1 atrioventricular conduction. After fluoroscopy-guided double trans-septal punctures, a high-density mapping catheter (PENTARAY©, Biosense Webster, CA, USA) and a Smarttouch SF irrigated-tip ablation catheter (Smarttouch SF©, Biosense Webster, CA, USA) were placed in the left atrium (LA), respectively. EAM was performed with the CARTO 3 CONFIDENSE system (Biosense Webster, CA, USA). Low voltage zones (LVZ) were defined as areas with a bipolar peak-to-peak voltage amplitude of <0.5 mV. Notably, LVZ were identified along the EpicorTM ablation line. However, there were multiple gaps in the ablation line, particularly located among the anterior segments of the right PV and the posterior wall (Figure 1). Activation mapping depicted 83% of the AT-CL with the earliest activation ostial of the LA appendage suggestive of a macro-reentry mechanism. The integration of vector and velocity information (COHERENTTM technology) confirmed a focal activation with a conduction block of the LA roof, as shown in Figure 2 and Supplement video 1. Ablation (30 Watts) was started at the earliest site of activation, resulting in prompt termination of the AT into sinus rhythm. Furthermore, the EpicorTM ablation line was completed by ablating the posterior wall and the anterior segments of the right PV. As a result, isolation of all PVs and the posterior wall was achieved (Figure 3).