Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): ZOLL Background The wearable cardioverter-defibrillator (WCD) is a temporary treatment option for patients at high risk for sudden cardiac death (SCD) in whom implantation of a cardioverter defibrillator (ICD) is temporarily not possible. Exercise training and rehabilitation has an IA recommendation in these patients. There are no data on safety and outcomes of patients with a WCD undergoing cardiac rehabilitation. Purpose The aim of this study is to evaluate the safety and feasibility of wearing a WCD while undergoing a cardiac rehabilitation program. Methods We performed a retrospective analysis of all patients with a successfully completed stationary rehabilitation program. Results 55/896 patients (6.1%) registered in the Austrian WCD registry completed a stationary rehab program (60±11 years, 1% female). Underlying cardiac disease was ischaemic cardiomyopathy (CMP) in 27/55 (49%), dilatative CMP in 15/55 (27%), inflammatory CMP in 10/55 (18%) patients. One patient had valvular CMP, one patient had tako tsubo CMP, one patient had a primary electrical disease (each 1,8%). The baseline LVEF at rehab start was 36% [12;80%], duration of rehab was 28 days [18;42] compared to a total prescription duration of 94 days [26;294]. 75.6% (41/55) patients completed a regular rehab duration with a WCD, 3.6% (2/55) got their WCD stopped during rehab due to recovery of the LV function, 21,8% (12/55) got a WCD prescribed during rehab. The daily wearing duration was 23.4h [12.6;23.9]. 2848 (mean 52±117/patient) automatic alarms and 340 (mean 6±9/patient) manual alarms were generated. Within this cohort 3,6% (2/55) patients had shocks for VT/VF during prescription: one patient for a VF event that was terminated with the first shock, another patient had three VT events that were also terminate with the first WCD shock. All events happened before rehabilitation, so no patient had a WCD treatment during rehab, neither appropriate, nor inappropriate. Two patient had recurrent stable VTs that were controlled with antiarrhythmic drugs during prescription, only one of them during rehab. 3 patients had a reported syncope during rehab, all of them associated with hypotension, one patient had an ambulatory check-up at the CIED clinic because of false automatic alarms due to artefacts. Following a relevant weight loss through rehab measurements, the fabric garment of the WCD had a poor fit and was adapted. The LVEF after rehab was 42% [23;73%]. At the end of WCD prescription 33/55 (60%) had a restitution of their cardiac function with no need for an ICD, 19/55 (35%) patients were implanted with an ICD. One patient (1,8%) had a heart transplantation, one patient (1,8%) had the desire to stop WCD prescription and one patient (1,8%) had a terminal non-cardiac disease. Conclusion Completing a cardiovascular rehabilitation program is feasible and safe for patients prescribed with a WCD and may contribute positively to the restitution of the cardiac function.

Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is an emerging method for atrial fibrillation (AF) ablation. However, there is little data about incidence, types, and predictors of AF recurrences after PFA for AF ablation. Methods We report our single-centre experience with PFA for AF ablation. Each procedure was performed under unconscious sedation with propofol and fentanyl. If needed, midazolam was added in rare cases. Fifteen minutes before transeptal puncture 70IU/kg of unfractionated heparin were administered, for an ACT level >300sec during the entire procedure. Isolation of pulmonary veins was started after administration of 1mg of atropine with 8 applications per vein (4 in basket, 4 in flower configuration). Afterwards all veins were checked for entrance- and exitblock to confirm isolation during SR. If needed, additional ablation was performed. Results In total, 124 patients undergoing AF ablation therapy with PFA between June 2021 to October 2022 were analysed. Mean age was 61±9 years, 39% were female. Mean CHADS-VASc Score was 2±1. Sixty-two percent had paroxysmal atrial fibrillation (PAF), 34% persistent AF, in 4% patients suffered from long standing persistent AF. In 85% (n=106) of procedures first pass isolation of all veins was possible. Primary success to achieve PV isolation was accomplished in all patients at the end of procedure. In addition to PVI, in 6,5% of patients cavotricuspid isthmus (CTI) was blocked, in another 7,3% the posterior wall was isolated during the first procedure. Mean procedure duration was 76±30 minutes, mean x-ray time 11±22 minutes. During 124 procedures, only one periprocedural complication was documented (vascular complication). Eighteen patients (14,5%) had recurrence of dysrhythmia after a blanking period of 3 months after a mean follow-up period of 167±150 days. Mean time to recurrence was 108±101 days. Patients with recurrences after the blanking period suffered significantly more often from diabetes (OR 0,21 (0,089-0,495); p>0.01) and hyperlipidaemia (OR: 0,198 (0,070-0,498); p>0.01). Until now we performed five re-do procedures of patients with recurrence of dysrhythmia after a PFA first-do procedure. The recurrent arrhythmia was AF (n=2), atypical AT (roof-dependent n=1, one mitral isthmus dependent n=1), and CTI-dependent flutter (n=1). All five patients had PV reconnections, and all could be successfully reablated. Conclusion AF ablation with PFA is associated with high SR success rate, and acceptable procedure duration and complication rates. Randomized studies are needed to further evaluate this new method compared with other ablation techniques.

Funding Acknowledgements Type of funding sources: None. Background Catheter ablation of atrial fibrillation is (AF) an established second line therapy for patients with symptomatic paroxysmal (PAF) and persistent AF (persAF). Novel ablation catheters with integrated thermocouples allow fast application of radiofrequency lesions with powers up to 90W. We aimed to describe primary and secondary outcomes after very high-power short duration (vHPSD) ablation. Methods 201 consecutive patients (127 PAF, 68 persAF, 6 longstanding persistent AF) underwent pulmonary vein isolation (PVI) using the QDOT Micro Catheter (Biosense Webster) with the ablation mode QMODE+ (90W, 4s, interlesion distance ≤4mm anterior, ≤6mm posterior). Results Mean age was 62±10 years, 38% were female, median CHA2DS2-VASc Score was 2 (0, 7). Median follow up duration was 196 (30, 461) days. 35% of patients had additional ablation of typical right atrial flutter. Primary success rate to achieve pulmonary vein isolation was achieved in all patients, no catheter-related complications (e.g., charring, steam pop) occurred. First pass isolation of all 4 PVs was achieved in 53% of patients, re-ablations were necessary in the carina regions (right: 27% of cases, left: 20%), 34% at multiple regions including the ridge, 12% in other regions around the PVs. Median procedure for PVI only were 110 (36-344) minutes. Arrhythmia-free survival was 79,3%. 21 patients underwent re-do procedures during follow-up showing most commonly showing gaps in the right PVs (RSPV 52%, RIPV 43%), the left inferior PV (48%), as well as the LSPV (38%) and the ridge (24%); with 91% of patients with recurrence showing more than one site reconnected. Conclusion Very high-power short duration ablation allows safe and quick pulmonary vein isolation. However, first pass isolation rate is low due to gaps in the carina regions. Arrhythmia-free survival is comparable to other pulmonary vein isolation techniques.