INTRODUCTIONRadiofrequency catheter ablation (RFCA) is a first-line therapeutic option for supraventricular tachycardia (SVT).(1) It is conventionally performed under fluoroscopy. The amount of exposure to fluoroscopy is highly dependent on multiple variables, such as operator experience and the complexity of the arrhythmia substrate.(2) As exposure to radiation during such procedures increases the lifetime risk of fatal malignancies, skin injuries and cataract, it poses a palpable hazard to both patients and medical staff.(3) This emphasises the importance of employing all possible measures to minimise exposure to ionising radiation.Recent advances in technology have led to the development of non-fluoroscopic three-dimensional (3D) mapping systems to guide ablation during prolonged electrophysiological procedures, such as pulmonary vein isolation for atrial fibrillation and mapping of atypical atrial flutter and ventricular tachycardia. These 3D mapping systems help physicians to better comprehend complex arrhythmias and develop appropriate ablation strategies. These systems have also been proven to substantially reduce ionising radiation exposure. Data on the use of non-fluoroscopic systems (NFS) in Singapore is limited. Therefore, the aim of the present study was to determine the consistency and applicability of the aforementioned latest findings in our local setting. The specific aims of the present study were (a) to determine the procedure and fluoroscopy times, and ionising radiation exposure of patients who underwent RFCA for SVT using NFS as compared to those using conventional fluoroscopy (CF); and (b) to compare atrioventricular nodal reentrant tachycardia (AVNRT) ablation and atrioventricular reentrant tachycardia (AVRT) ablation. METHODSThe present study was a prospective analysis of patients who underwent electrophysiology (EP) study of paroxysmal SVT at our institution from January 2012 to March 2014. Patients with AVNRT and AVRT were enrolled and a total of 200 consecutive patients, aged 11-86 years, who underwent RFCA were included in this study. All patients (or parents, if the patient was underage) gave informed consent.Each patient underwent RFCA in the fasted and non-absorptive state, and under intravenous sedation with midazolam and fentanyl. Local anaesthetic with lignocaine was administered at the vascular access sites, which were the femoral venous site for all patients. Some patients also had femoral arterial access if the operator selected a retrograde aortic approach to obtain access to the left side of the heart. The decision for NFS usage was operator-dependent and made before the EP study. The choice of NFS, either EnSite TM NavX