Introduction
Paroxysmal supraventricular tachycardia (PSVT) refers to cardiac arrhythmias originating above the ventricle that results in sudden rapid heart rate episodes. More than 90% of PSVTs are atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT) or Wolff-Parkinson-White (WPW) syndrome, which are caused by abnormal electrical extra pathways in heart, including slow pathways (SP) or accessory pathways (AP).1 Catheter-based radiofrequency ablation (RFA) of these extra pathways is highly effective for the treatment of PSVTs. The procedure is often successful, but sometimes it becomes complicated when accurate localization of SP or AP is difficult.2 Location of the ablation target is determined based on anatomical markers and electrical potentials, and obtaining adequate electrograms at ablation sites is important for effective ablation of PSVTs.2, 3
Mapping resolution of the ablation catheter is dependent on electrode size and spacing. A novel ablation catheter (IntellaTip MiFi OI, Boston Scientific, Boston, MA, USA) has three additional, radially-distributed mini electrodes (MEs) located 1.3 mm from the distal tip that offer high-resolution electrograms close to ablation sites. The ME-equipped ablation catheter provides more precise localization of the actual ablation site. It has been shown to be helpful to avoid unnecessary radiofrequency application for cavotricuspid isthmus ablation in previous clinical studies.4, 5 The ME signals visualized in ablation catheter can be advantageous for accurate localization of SP or AP and identification of discrete pathway electrograms during RFA for PSVTs. This study aimed to evaluate the mapping performance and efficacy of novel ablation catheters equipped with MEs compared to conventional ablation catheters, in RFA for AVNRT or AVRT/WPW syndromes.