OR01 2. Pacemaker, defibrillator and electrophysiology Radiofrequency catheter ablation of atrial fibrillation since 2001: did we improve? H. Servatius* 1, L. Roten1, J. Seiler1, F. Noti1, V. N. Tran1, A. Medeiros Domingo1, A. Haeberlin1, A. Lam1, J. Fuhrer1, H. Tanner1 1Department of Cardiology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland Introduction: Since the introduction of catheter ablation (CA) of atrial fibrillation (AF), knowledge has increased and techniques and technologies have developed. The aim of our analysis was to investigate, whether these advances resulted in reduced recurrence rates of atrial tachyarrhythmias over time. Methods: From 2001 to 2014, all patients undergoing a first radiofrequency (RF) CA of AF at our institution were analyzed using our prospective AF registry. Patients were included if an objective follow-up (FU) using serial 7-days- ECGs or a 12-lead-ECG in case of recurrence were available. The follow-up period was 12 months in all patients to allow for comparison over time, and because the recommended long-term ECG FU was most dense within the first year (3, 6 and 12 months). A blanking period of 3 months was applied. Recurrence was defined as any atrial tachyarrhythmia lasting > 30 seconds, irrespective of symptoms. Results: Out of 883 patients undergoing a first RF CA of AF, 766 (87%) fulfilled inclusion criteria. Paroxysmal AF was present in 529 (69%) and persistent AF in 237 (31%). Mean age of the study population was 58±10 years and 577 (75%) were males. The recurrence rates in patients with paroxysmal and persistent AF are given in the figure. A decrease of recurrence was observed in both groups, but it was more pronounced in patients suffering from paroxysmal AF. Picture/Graph: Conclusion: These single center real world data show that all combined advances and developments of RF CA of AF resulted in a decrease of recurrence rates over time within the first year after ablation. This decrease was more pronounced in patients with paroxysmal AF. However, there is still room for improvement. Disclosure of Interest: H. Servatius Grant/ research support from: Biosense Webster, SJM, Sorin, L. Roten Grant/ research support from: Biosense Webster, BostonScientific, J. Seiler Grant/ research support from: Biosense Webster, BostonScientific, F. Noti: None Declared, V. N. Tran: None Declared, A. Medeiros Domingo Grant/ research support from: Sorin, A. Haeberlin: None Declared, A. Lam: None Declared, J. Fuhrer Grant/ research support from: AstraZeneca, Bayer, Bristol-Myers Squipp, Medtronic, SanofiAventis, Sorin, Biosense Webster, SJM, BostonScientific, Biotronik, H. Tanner Grant/ research support from: Biosense Webster, SJM, BostonScientific, Biotronik OR02 2. Pacemaker, defibrillator and electrophysiology Reduction of radiation exposure during cryoballoon ablation of atrial fibrillation M. Kühne* 1, S. Knecht1, T. Reichlin1, A. Mühl1, B. Schaer1, S. Osswald1, C. Sticherling1 1University of Basel, Basel, Switzerland Introduction: Contrast injections to demonstrate pulmonary vein (PV) occlusion are routinely performed during cryoballoon (CB) ablation of atrial fibrillation (AF). The aim of this study was to assess the feasibility and impact of a procedural protocol without routine cine acquisitions and without contrast injections during CB ablation of AF. Methods: Consecutive patients with paroxysmal AF undergoing pulmonary vein isolation (PVI) using a 2nd generation CB and a single 3-minute freeze approach were studied. Patients undergoing PVI using a novel procedural protocol without routine contrast injections and without cine acquisition (group 1) were compared to a set of consecutive patients undergoing PVI with routine contrast injections and cine acquisitions to demonstrate PV occlusion (group 2). The main outcome measures were the feasibility of the low radiation procedural protocol and the impact of the protocol on radiation dose (dose area product, air kerma), fluoroscopy time, procedure time, mid-term efficacy and safety. Results: Twenty-four patients (age 61±10 years, ejection fraction 0.61±0.07, left atrial size 40±7 mm) with paroxysmal AF were included. Baseline data were not significantly different between the groups. In group 1, the novel low-radiation protocol was feasible in 11 of 12 patients (92%), and median contrast use was 0 ml (IQR 0-0) compared to 35 ml (IQR 23- 48) in group 2 (p<0.0001). Dose area product was 2.0 (1.7-3.8) Gy*cm2 in group 1 compared to 7.8 (3.2-16.5) Gy*cm2 in group 2 (p<0.05). Total procedure time and fluoroscopy time were 54±9 minutes and 9.3±3.0 minutes in group 1 and 72±10 minutes and 13.8±4.0 minutes in group 2, respectively (all p<0.05). There were no complications in both groups. Freedom from AF after a single procedure was 83% (10/12) in the low-radiation group compared to 75% (9/12) in group 2 after a follow-up of 6 months (p=ns). Conclusion: Performing CB ablation without using contrast injections and without cine acquisitions to demonstrate PV occlusion is feasible in the majority of patients and is associated with nearly 4-fold decrease in radiation exposure. Disclosure of Interest: M. Kühne Grant/ research support from: Biosense Webster, Consultant for: Bayer, Daiichi- Sankyo, Paid Instructor for: Medtronic, S. Knecht: None Declared, T. Reichlin: None Declared, A. Mühl: None Declared, B. Schaer: None Declared, S. Osswald: None Declared, C. Sticherling: None Declared OR03 2. Pacemaker, defibrillator and electrophysiology Catheter ablation of ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy – experience of a tertiary care center N. Schenker* 1, A. M. Saguner1, S. Mathew1, R. Tilz1, E. Wissner1, A. Metzner1, C. Lemes1, T. Maurer1, C. Heeger1, T. Fink1, F. Santoro1, K. Hayashi1, K.-H. Kuck1, F. Ouyang1 1Asklepios Klinik St. Georg, Hamburg, Germany Introduction: Sustained Ventricular Tachycardia (VT) is common in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC/D), and associated with frequent ICD interventions, hospitalizations, and reduced quality of life. Antiarrhythmic drugs are not always effective in suppressing ventricular arrhythmias in ARVC/D. Aim: We assessed outcomes of radiofrequency catheter ablation (RFA) for VT in a single-center cohort of patients with ARVC/D. Methods: All RFA procedures addressing VT performed in our tertiary-care center between 1998 and 2015 in 40 patients (49±16 years of age; 83% male) with definite (n=32) or borderline (n=8) ARVC/D were analyzed. Results: 71 RFA procedures using a 3D mapping system were performed (mean 1.8 per patient), of these 55% (n=39) using an endocardial, 34% (n=24) using a combined endo-epicardial, and 11% (n=8) using an epicardial approach (table). VT was inducible in 86% of patients. In 44% of ablations, >1 sustained VT was inducible, and multiple VT morphologies (mean 1.5±1) were common (38%). The mean cycle length of induced VT was 351±78ms. Most VT had a LBBB morphology and superior axis, correlating with the subtricuspid area as the most frequent VT exit site. Although fibro-fatty infiltration typically begins subepicardially, an endocardial substrate with low voltage (bipolar <1.5 mV) and fragmented/late potentials was found in the majority (55%). RFA was successful (defined as abolishment of all inducible sustained VTs) in 86%, and partially successful (defined as abolishment of all clinical VTs) in 10%. 3 procedures on two different patients were not successful. VT ablation was generally safe with 1 (1.4%) pericardial tamponade occurring after epicardial puncture, and 9 minor complications (pericardial effusion n=2, mild pericarditis n=4, mild femoral hematoma n=3). The number of sustained VT significantly decreased after RFA compared to before RFA (27±38 vs. 4±12, p<0.05). The percentage of patients on antiarrhythmic drugs did not change before and after RFA (93% vs. 90%, p=ns). Picture/Graph: Conclusion: RFA is an effective strategy to reduce VT burden in patients with ARVC/D. Although the pathologic process begins in the subepicardium, the majority of patients referred for VT ablation has rather advanced disease, and thus presents with an endocardial substrate amenable to endocardial RFA. Endocardial RFA has a high acute success rate, potentially obviating the need for an epicardial approach in some of these patients. Disclosure of Interest: None Declared OR04 2. Pacemaker, defibrillator and electrophysiology Propensity-score weighted analysis of irrigated-tip catheter ablation of typical atrial flutter using standard irrigated platinum-iridium, porous irrigated platinum-iridium and irrigated gold-tip catheters S. Knecht1, F. Burch* 1, A. Mühl1, T. Reichlin1, U. Celikyurt1, B. Schaer1, D. Altmann2, P. Ammann2, S. Osswald1, C. Sticherling1, M. Kühne1 1Cardiology, University Hospital Basel, Basel, 2Kantonsspital St Gallen, St. Gallen, Switzerland Introduction: Numerous irrigated ablation catheters are currently available for the ablation of atrial flutter (AFL). The aim of this study was to compare 3 different irrigated-tip catheters used for ablation of AFL. Methods: An observational dataset of consecutive patients referred for radiofrequency (RF) ablation of AFL from two centers was analysed using a propensity score weighting method to reduce potential confounding. Two analyses were performed: 1) A comparison of the established irrigated platinum-iridium tip catheter (Thermocool, group 1) to the pooled group of the more recent designs of a porous irrigated (56 irrigation holes) platinum-iridium