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Introduction: Data about atrial fibrillation (AF) ablation using high-power short duration (HPSD) radiofrequency ablation in the elderly population is still scarce. The aim of our study was to investigate the efficacy and safety of HPSD ablation in patients over 75 years compared to younger patients.Methods: Consecutive patients older than 75 years with paroxysmal or persistent AF undergoing a first-time AF ablation using 50 W HPSD ablation approach were analyzed in this retrospective observational analysis and compared to a control group <75 years. Short-term endpoints included intraprocedural reconnection of at least one pulmonary vein (PV) and intrahospital and AF recurrence during 3 months blanking period, as well as a long-term endpoint of freedom from atrial arrhythmias of antiarrhythmic drugs after 12 months.Results: A total of 540 patients underwent a first AF ablation with HPSD (66 ± 10 years; 58% male; 47% paroxysmal AF). Mean age was 78 ± 2.4 and 63 ± 6.3 years (p < .001), respectively. Elderly patients were significantly more often women (p < .001). The procedure, fluoroscopy, and ablation were comparable. Elderly patients revealed significantly more often extra-PV lowvoltage areas requiring additional left atrial ablations (p < .001). Overall complication rates were low; however, elderly patients revealed higher major complication rates mainly due to unmasking sick sinus syndrome (p = .003).Freedom from arrhythmia recurrences was comparable (68% vs. 76%, log-rank p = .087). Only in the subgroup of paroxysmal AF, AF recurrences were more common after 12 months (69% vs. 82%; log-rank p = .040; hazard ratio: 1.462, p = .044) in the elderly patients. In multivariable Cox regression analysis of the whole cohort persistent AF, female gender, diabetes mellitus and presence of left atrium low-voltage areas, but not age >75 years were associated with AF recurrences.Conclusion: HPSD AF ablation of patients >75 years in experienced centers is safe and effective. Therefore, age alone should not be the reason to withhold AF ablation

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Funding Acknowledgements Type of funding sources: None. Background Data about VT ablation in patients with electrical storm (ES) is limited. This study sought to compare the prognostic outcome of patients undergoing VT ablation after electrical storm with and without a septal substrate on mortality, VT recurrence rates, rehospitalization rates and major adverse cardiac events (MACE). Methods In this large single-centre study patients presenting with ES and undergoing VT ablation were included from June 2018 to April 2021. Patients with septal substrate were compared to patients without septal substrate. The primary prognostic outcome was cardiovascular mortality, secondary endpoints were VT recurrence rates, rehospitalization rates and MACE all after a median follow-up of 22 months. Results A total of 108 patients underwent a first VT ablation due to electrical storm and were included (65 ± 13 years; 86% male; 45% ischemic cardiomyopathy). Cardiovascular risk factors were equally distributed among both groups (all p&gt;0.05). Major complications occurred in 11% of all patients with increased postinterventional third degree AV blocks among patients with septal substrate (9% vs 0%; p=0.062). Noninducibility of the clinical VT was achieved in 98% of all patients without a septal substrate and in 91% of all patients with a septal substrate (p=0.136). Noninducibility of any VT was achieved in 88% without a septal substrate and in 66% with a septal substrate (p=0.011). However, in non-invasive programmed stimulation before hospital discharge VT inducibility did not differ among both groups (p&gt;0.05). After 1 year and a median of 22 months follow-up, patients with septal substrate died significantly more often due to cardiovascular causes (25% vs. 7%; log-rank p=0.021). In univariate analysis cardiovascular mortality for ES patients with septal substrate was 3.9 fold higher (HR 3.979; CI 95% 1.124 – 14.092; p=0.032). Independent predictors of adverse outcome in multivariable regression analysis were presence of septal substrate (HR 4.836; p=0.026) and increased numbers of VTs inducible during VT ablation (HR 1.635; p=0.007). VT recurrence during follow-up was 59% and equally distributed among both groups (log rank p=0.911). Rehospitalization rates (log rank p=0.532) and rates of MACE (log rank p=0.463) were equal. Conclusions Presence of a septal substrate is associated with adverse long-term cardiovascular mortality in patients admitted for VT ablation after electrical storm. Despite decreased ablation success in these patients VT recurrence rates were not increased during follow-up.

Introduction: Silent cerebral events (SCE) have been identified on magnetic resonance imaging (MRI) in asymptomatic patients after atrial fibrillation (AF) ablation. Silent cerebral lesions represent irreversible cerebral damage, comparative analysis using a consistent MRI definition is missing and factors influencing the risk of SCE are poorly understood. Methods: 351 Patients undergoing AF ablation underwent post-ablation cerebral MRI. SCE were identified based on a sensitive definition using a 1.5Tesla MRI including DWI and ADC-map (but not including FLAIR). AF ablation was performed either using irrigated single-tip radiofrequency (RF) ablation (group 1, N=73), phased RF pulmonary vein isolation (PVI) (group 2, N=129), endoscopically-guided laser balloon (group 3, N=41), cryo-balloon PVI (group4, N=34) and irrigated RF multipolar catheters (nMARQ) (group 5, N=73). Differences in regard to SCE rates were analyzed. Results: In group 1 22%, in group 2 37%, in group 41%, in group 4 21% and in group 5 27% of patients had documented SCE. There was a significantly higher incidence of SCL in patients with compared to without exchanges of catheters over a single transseptal sheath (34% vs. 18%, p=0.007) and in patients with left atrial dilation (48% vs. 30%, p=0.01). In a subgroup analysis incidence of SCE was lower when patients were ablated under continued oral anticoagulation (11%) compared to novel oral anticoagulants (33%) or without continuous appropriate anticoagulation bridged with low-molecular weight heparin (45%). Documented left atrial low-voltage areas were associated with a higher incidence of SCE (46% versus 24% in the control group). Conclusions: When using a sensitive MRI definition of SCE incidences are relevantly higher compared to using the “old” definition including the FLAIR-sequence. Technology-associated and procedural characteristics associated with a higher risk of SCE have been identified. Modification of procedural steps of the AF ablation procedure may further reduce the risk of SCE.