Background Based on the assumption of trigger elimination, pulmonary vein isolation (PVI) currently presents the gold standard of atrial fibrillation (AF) ablation. Recently, rapidly spinning rotors or focal impulse formation has been raised as a crucial sustaining mechanism of AF. Ablation of these rotors may potentially obviate the need for trigger elimination with PVI. Purpose This study sought to compare the safety and effectiveness of Focal Impulse and Rotor Modulation (FIRM) guided catheter ablation only with the gold standard of pulmonary vein isolation (PVI) in patients with paroxysmal AF. Methods This was a post-market, prospective, single-blinded, randomized, multi-center trial. Patients were enrolled at three centers and equally (1:1) randomized between those undergoing conventional RF ablation with PVI (PVI group) vs. those treated with FIRM-guided RF ablation without PVI (FIRM group). Data was collected at enrollment, procedure, and at 7-day, 3-month, 6-month, and 12-month follow-up visits. The study was closed early by the sponsor. At the time of study closure, any pending follow-up visits were waived. Results From February 2016 until February 2018, a total of 51 (out of a planned 170) patients (mean age 63±10.6 years, 57% male) were enrolled and randomized. Four patients withdrew from the study prior to treatment, resulting in 23 patients allocated to the FIRM group and 24 in the PVI group. Only 13 patients in the FIRM group and 11 patients in the PVI group completed the 12-month follow-up. Statistical analysis was not completed given the small number of patients. Single-procedure effectiveness (freedom from AF/atrial tachycardia recurrence after blanking period) was 52.9% (9/17) in the FIRM group and 85.7% (12/14) in the PVI group at 6 months; and 31.3% (5/16) in the FIRM group and 80% (8/10) in the PVI group at 12 months. Repeat procedures were performed in 45.8% (11/24) patients in the FIRM group and 7.4% (2/27) in the PVI group. The acute safety endpoint [freedom from procedure-related serious adverse events (SAE)] was achieved in 87% (20/23) of FIRM group patients and 100% (24/24) of PVI group patients. Procedure related SAEs occurred in three patients in the FIRM group: 1 femoral artery aneurysm and 2 injection site hematomas. No additional procedure-related SAEs were reported >7 days post-procedure. Conclusions These partial study effectiveness results reinforce the importance of PVI in paroxysmal atrial fibrillation patients and suggest that FIRM-guided ablation alone (without PVI) is not an effective strategy for treatment of paroxysmal AF in most patients. Further study is needed to understand the effectiveness of adding FIRM-guided ablation as an adjunct to PVI in this patient group. Acknowledgement/Funding Abbot

Funding Acknowledgements Type of funding sources: None. Background Catheter ablation for atrial fibrillation (AF) treatment provides effective and durable PVI associated with encouraging clinical outcome. The novel QDot ablation catheter with Qmode + ablation mode (90W/4sec, Figure 1) offers the ability to possibly improve safety and decrease ablation procedure times. Aims We aim to evaluate safety and efficacy of the very high-power short-duration (vHP-SD) temperature-controlled radiofrequency (RF) ablation Qmode + mode for pulmonary vein isolation (PVI) utilizing the novel QDot micro ablation catheter. The data was compared to conventional power-controlled ablation index (AI) guided PVI. Methods Twenty-five consecutive patients with paroxysmal or persistent AF were prospectively enrolled, underwent vHP-SD based PVI (vHP-SD group) and were compared to 25 consecutive patients treated with conventional CF-sensing catheters (control). Results All PVs were successfully isolated utilizing Qmode +. The total median RF ablation time was vHP-SD: 334 (282, 369) sec. vs control: 1567 (1250, 1756) sec. (p < 0.0001), the median procedure time was vHP-SD: 56 (48-62) vs. control: 104 (92-122) min (p < 0.0001). No differences in periprocedural complications were observed. Conclusions The novel Qmode + provides safe and effective PVI with impressive short RF time and short procedures times. Procedure time and RF time were substantial lower in the vHP-SD group. Abstract Figure 1

Funding Acknowledgements Type of funding sources: None. Background The arctic front cryoballon (AF-CB) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome data. The POLARx cryoballoon incorporates unique features which may translate into improved efficacy and safety. Purpose To assess efficacy and safety of the novel POLARx cryoballoon in comparison to the fourth generation arctic front cryoballon (AF-CB4). Methods Twenty-five consecutive patients with paroxysmal or persistent atrial fibrillation (AF) were prospectively enrolled, underwent POLARx based PVI (POLARx group) and were compared to 25 consecutive patients treated with the fourth generation AF-CB (AF-CB4 group). Results A total of 100 (POLARx) and 97 (AF-CB4) pulmonary veins (PV) were identified and all PVs were successfully isolated utilizing the POLARx and AF-CB4, respectively. A significant difference regarding the mean minimal cryoballoon temperatures reached using the AF-CB4 and POLARx (-50 ± 6°C vs. -57 ± 7°C, p = 0.004) was observed. Real-time PVI was visualized in 81% of POLARx patients and 42% of AF-CB4 patients (p < 0.001). Despite a certain learning curve utilizing the POLARx a trend towards shorter median procedure time (POLARx: 45 (39, 53) minutes vs. AF-CB4: 55 (50, 60) minutes (p = 0.062) was found. No differences were observed for periprocedural complications. Conclusions The novel POLARx showed similar safety and efficacy compared to the AF-CB4. A higher rate of real-time electrical PV recordings and significantly lower balloon temperatures were observed using the POLARx as compared to AF-CB4.

Funding Acknowledgements Type of funding sources: None. Background Although pulmonary vein isolation (PVI) is an effective treatment strategy for patients with paroxysmal atrial fibrillation (AF), it is associated with limited success rates in patients with persistent AF (PersAF). In this context the left atrial appendage (LAA) was recently identified as a target of catheter ablation especially in PVI non-responders. Although effective, this strategy may cause electromechanical dissociation and was therefore assumed to be associated with an increased risk of thromboembolism despite oral anticoagulation (OAC). Since RF based LAAI showed increased rates of thromboembolism and stable LAAI is difficult to achieve in some cases, Cryoballoon-based LAAI might offer a valuable option to achieve safe and durable LAAI. Recently the fourth generation cryoballoon was introduced. Additionally, the 40% shorter tip potentially increases the safety profile as well as efficacy of CB-based LAAI. Objective To assess safety and efficacy on CB2 vs CB4 based LAAI. Methods Cryoballoon based PVI and LAAI was performed in 20 patients with PersAF and long-standing PersAF. The first 10 consecutive patients were treated by the second-generation cryoballoon (CB2) the last 10 patients were treated by the CB4. LAAI was performed by utilizing a bonus freeze protocol (freezing time 300 seconds + another 300 seconds after LAAI). Results Stable LAAI was achieved after a mean of 2.6+/- 1.7 cryoballoon applications with a mean minimal temperature of -52+/-6 °C. Unless one phrenic nerve palsy (5.6%) of the left phrenic nerve no further periprocedural complications occurred. Successful LAAI was performed in 19/20 (95%). TEE after 6 weeks detected LAA thrombus in 3/10 (30%) patients (CB2 group) and 3/10 patients (30%) (CB4 group), p = 0.99. Successful LAA-closure was performed in 16/20 patients (80%) after a mean of 75+/-59 days. The LAA was durable isolated in 8/9 patients (89%, CB2) and 6/8 patients (75%, CB4), p = 0.56). AF recurrence after 6 weeks was 1/10 (10%, CB2) and 3/9 (33%, CB4), p = 0.26. Conclusions Here we used – to our knowledge – for the first time a CB4 for LAAI, followed by a combined check for LAAI and LAA-closure after 6 weeks, compared to the CB2. LAAI was successfully isolated by both cryo-balloons in the majority of patients. Hence the use of newest cryo-balloon generation for LAAI seems a safe and successful procedure compared to earlier balloon generations. However, a relatively high rate of LAA-Thrombus was detected after LAAI. Therefore, LAA closure is mandatory in this population.

Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is a novel non-thermal energy source with promising safety and efficacy advantages compared to standard ablation technologies. Purpose We aimed to develop a safe, effective and fast pulmonary vein isolation (PVI) utilizing a single shot PFA catheter via a single femoral vein puncture and a venous closure system approach. Methods Forty-eight consecutive AF patients underwent first-time PVI via PFA under deep sedation. A single ultrasound guided femoral vein puncture and a single transseptal puncture was utilized for left atrial access. After pulmonary vein (PV) angiography eight pulse trains (2kV/2.5 sec, bipolar, biphasic, each 4x basket/flower configuration) were delivered to each PV. Extra pulse trains in the flower configuration (8x) were added to the posterior wall for very wide antral circumferential ablation (vWACA). Continuous intraluminal esophageal temperature (TESO) was monitored with a s-shaped esophageal temperature probe. A venous closure system was utilized on the single access site. A Donati suture was performed. The pressure bandage was removed after 1h. Results Patients (mean age: 64 +/-11 years) presented with AF (paroxysmal 58% or persistent AF (42%). A total of 192 PV were identified and isolated via PFA (100%). A mean of 40 pulse trains for PVI and vWACA have been used. The mean procedural time was 27 +/- 7 minutes, the mean catheter dwell time was 14 +/- 6 minutes and the median fluoroscopy time was 6 +/- 2 minutes. No relevant esophagus temperature rise occurred. One patient (2%) experienced a transient phrenic nerve palsy which recovered until the end of the procedure. Two patients (4%) experienced a superficial bleeding which was treated by a figure of eight suture. No severed hematoma, transfusion or intervention was necessary. No pericardial effusion or tamponade occurred. Conclusion The combination of a single vein single transseptal puncture approach resulted in a 100% rate of acute PVI and an extraordinary fast procedure and dwell time. The rate of periprocedural complications was low.