Funding Acknowledgements Type of funding sources: None. Background Electric conduction disturbances are very common, however, patients in need for ventricular pacing may suffer from pacing-induced heart failure due to unphysiological pacing by the right ventricular lead. Conducting system pacing allows to overcome this common issue with a more physiologic approach, but real-life procedural data using this technology is scarce. Methods We report a single centre experience of the first 63 consecutive patients being implanted with a His-bundle-based pacemaker 09/2020-11/2022 per 3D-mapping guided implantation due to bradyarrhythmia, or for cardiac resynchronisation therapy in heart failure combined with a left-ventricular lead (HOT-CRT) ± a right ventricular defibrillator lead. The identification of the His-bundle-location was done with a 3D electroanatomic mapping system via an introducing sheath that is provided with electrodes at its tip. Results Mean age was 71 [18;87] years, 18/63 (29%) patients were female, mean baseline LVEF was 46±15%. Baseline ECG was captured before implantation: QRS width was 127±34ms, with typical LBBB in 19/63 (30%), typical RBBB in 5/63 (8%), alternating BBB in two patient (3%) and either no BBB or ventricular escape rhythm in 37/63 (59%). Indications for implantation were AV-block grade II-III in 31/63 (49%), primary prophylactic ICD indication in HFrEF in 18/63 (29%), atrial fibrillation with bradycardic conduction in 8/63 patients (13%), sick-sinus-syndrome in 4/63 (7%) and secondary prophylactic ICD indication in one patient (2%). In 57/63 (90,5%) a primary device was implanted, in 6/63 (9,5%) a pre-existent device was upgraded with a HB lead. Therefore, 23 dual-chamber-pacemaker, 5 single-chamber-pacemaker, 10 single-chamber CRT-P, 17 dual-chamber CRT-P, 4 single-chamber CRT-D, 4 dual-chamber CRT-D were implanted. In 63 patients his bundle pacing was attempted, while in 6/63 (9%) patients outside of this analysis the attempt was not successful, these patients were consecutively implanted with a non-HBP-device and therefor excluded from the further analysis. In the 63 patients included in this analysis with a primary successful pacing at the his-position, 5/63 (8%) his-bundle-leads dislocated within the first 48 hours, leading to a secondary success rate of 92%. There were two post-procedural pneumothorax that needed drainage, no major procedure-related complications occurred. Median skin-to skin procedure time was 111±47 minutes in his-bundle-device-implantation. The paced QRS width at the post-implantation follow up was 113±27ms with a change in QRS width of -15±39ms (+72; -92ms). The mean his-bundle sensing was 5,38±5,6mV and the mean threshold 1,1±0,86V over 1,0±0,5ms (0,4;1,5ms). The proportion of ventricular pacing was 75±36%. Conclusion Electroanatomic-guided His bundle pacing as a new innovative technic for physiological pacing is viable including high implantation success rate as well as electric impact, both regarding QRS width and pacing threshold.

Funding Acknowledgements Type of funding sources: None. The incidence of early atrial fibrillation (AF) recurrence within the first week after AF ablation and its predictive value for late AF recurrences are unclear. TeleCheck-AF is a remote on-demand mobile health (mHealth) infrastructure, which is based on a mobile phone app using photoplethysmography (PPG) technology (Fibricheck) allowing rate and rhythm monitoring through teleconsultations. The feasibility and clinical implications of PPG telemonitoring specifically during the first week after atrial fibrillation ablation is unknown. Methods Within the TeleCheck-AF project, the Medical University offered a total of 382 consecutive patients undergoing AF ablation (between June 1st 2020 and December 15th 2021) photoplethysmography (PPG) telemonitoring with "FibriCheck" during the first week after the ablation procedure. Patients received a QR code for activation of the software on their smartphone and were connected to the clinician’s telemedicine portal. They were instructed to perform rhythm monitoring three times per day and in case of symptoms. Clinicians assessed the tracings and contacted the patients if therapeutic steps were indicated. Results In total, 119 patients (31%) agreed to perform telemonitoring after ablation. Patients undergoing telemonitoring were younger compared to those who refused participation (58±10years vs. 62±10years, p<0.001). 34% were female, median CHA2DS2-VASc-Score was 1 (0-6). 62% of patients had paroxysmal AF and 37% had persistent AF. One of four patients (24%) had already undergone previous ablations. Most index ablations were radiofrequency ablations (89%; 7% cryo; 4% pulsed field ablation). Median follow up duration was 281 (16-620) days. 27% of patients had tracings suggestive of AF in the week following the index ablation. Telemonitoring resulted in clinical interventions ins 24% of patients: amiodarone was started in 8%, class I antiarrhythmic drugs were up titrated in 7%, cardioversion was scheduled in 5%, antiarrhythmic drugs were reduced due to symptomatic bradycardia in 3% of patients. During follow-up, 22% of patients had ECG-documented AF recurrences. PPG recordings suggestive of AF in the week after ablation were predictive of late recurrences (p<0.001). Conclusion Rhythm monitoring with a PPG-based mHealth application was feasible and often resulted in clinical interventions. Due to its high availability, PPG-based follow-up actively involving patients after AF ablation may close a diagnostic and prognostic gap and increase active patient-involvement. Figure 1: Schematic overview of the telemonitoring process. After the ablation, the patient measures PPGs for one week, dashboard view for clinician shows regular rhythm (green, atrial fibrillation (red) and unclear tracings (blue).

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 126 consecutive patients (78 PAF, 43 persAF, 5 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±9 years, 33% were female, median CHA2DS2-VASc Score was 2 (0, 7). Median follow up duration was 204 (14, 461) days. 30% 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 48% of patients, re-ablations were necessary in the carina regions (right: 37% of cases, left: 29%) and ridge (14%). Median procedure for PVI only were 102 (45-210) minutes. Arrhythmia-free survival was 79,6% (see Figure 1). Eight patients underwent re-do procedures during follow-up showing most commonly showing gaps in the right inferior PV (63%) and ridge (50%). 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. Figure 1: Left panel: Sample image of a vHPSD-PVI, posterior view of the left atrium. Right panel: Single procedure arrhythmia-free survival after vHPSD-PVI.

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.