Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation of VTs and intramyocardial substrate (IS) remains a challenge that may require alternative mapping and ablation strategies such as bipolar ablation (BA) to achieve VT non inducibility. However, the long-term success of these alternative strategies is still uncertain. Purpose The aim of this study was to report the midterm center experience success of BA RF ablation of VT in patients with documented intramyocardial scar in cardiac imaging. Methods 19 patients with documented intramyocardial substrate on cardiac imaging (cardiac MRI or cardio CT with delayed enhancement) and VT recurrences after at least one conventional catheter ablation were retrospectively included. The intraprocedural success (i.e. VT non inducibility at the end of procedure) respectively midterm success (i.e VT recurrence after 6 months from BA) were investigated. The ablation was performed using a special RF generator which permits bipolar RF ablation between 2 irrigated catheters. Results A total number of 19 patients were included (100 % men, mean age 66,7 ± 9,16 y/o). The mean LVEF was 39,5 ± 5,7. The distribution of underlying structural heart disease was as follow: 21 % ischemic cardiomyopathy (4 out of 19 patients), 52 % dilative cardiomyopathy (10 out of 19 patients) respectively 26 % other etiologies (5 out of 19 patients). A mean number of 2 ± 1 conventional VT ablation were previously performed. In almost all patients (94 %, 18 out of 19 patients) the clinical VT was induced before the BA (mean CL 342 ± 91ms). The BA was performed predominantly septal (84%, 16 out of 19 patients). In 3 patients an endo/epicardial BA was performed. No VT was inducible any more at the end of procedure in 15 patients (79 %). At a mean follow up of 1 ± 0,5 years no recurrence of clinical VT was noted but non-clinical VT recurrence was seen in 9 patients (47 %) exclusively in patients with septal substrate. Conclusion BA represents a good alternative strategy for CA in patients with IS and failed conventional VT ablation with good acute success but high VT recurrence rate in patients with septal IS. Intramural LGE on lateral LV wall Epi/endocardial ablation catheters

Abstract 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 with ES to those with ventricular tachyarrhythmias but without ES undergoing VT ablation 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 from June 2018 to April 2021 were compared to patients undergoing VT ablation due to ventricular tachyarrhythmias but without ES. 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 311 patients underwent a first VT ablation due to ventricular tachyarrhythmias and were included (63 ± 14 years; 86% male). Of them 108 presented with ES. In the ES cohort dilated cardiomyopathy as underlying heart disease was significantly increased (p=0.008), whereas all other cardiomyopathies were equally distributed. Major complications were equal among both groups (p>0.05). Ablation of the clinical VT was achieved in 95% of all patients without ES and in 94% of all patients with ES (p>0.05). Noninducibility of any VT was achieved in 91% without ES and in 76% with ES (p=0.001). This was also reflected in higher VT induction rates in non-invasive programmed stimulation before hospital discharge among ES patients (40% vs. 19%; p=0.031). After a median of 22 months of follow-up, patients with ES revealed slightly increased cardiovascular mortality rates (17% vs. 9%; log-rank p=0.061; HR 1.902; CI 95% 0.961 – 3.765; p=0.061). Furthermore, ES patients suffered from increased VT recurrence rates (59% vs. 40%; log rank p=0.006), rehospitalization rates (73% vs. 49%; log rank p=0.001) and MACE (71% vs. 45%; log rank p=0.001). ES patients displayed a 1.7-fold increased risk for VT recurrence (HR 1.701; CI 95% 1.160 – 2.493; p=0.006), a 1.9-fold increase for rehospitalization (HR 1.885; CI 95% 1.366 – 2.600; p=0.001) and a 1.9-fold increase for occurrence of MACE (HR 1.935; CI 95% 1.398 – 2.679; p=0.001). Presence of ES was the only independent predictors of VT recurrence and occurrence of MACE, whereas ES and decreased LVEF were independent predictors of rehospitalization. Conclusions VT ablation in patients with ES is challenging and these patients reveal highest risk for recurrent VTs, rehospitalization and MACE. These patients need close follow-ups and optimal guideline-directed therapy.

Ventrikuläre Extrasystolen (VES) stellen in den meisten Fällen eine benigne Art von Herzrhythmusstörungen dar, die am häufigsten aus dem rechts- oder linksventrikulären Ausflusstrakt stammen und die zufälligerweise im Elektrokardiogramm (EKG) dokumentiert werden. Dennoch spielen die Anamnese, die Vorgeschichte des Patienten bzw. eine kardiale Bildgebung eine entscheidende Rolle in der Differenzierung zwischen benignen vs. malignen (d. h. assoziiert einer vorliegenden strukturellen Herzerkrankung) VES. Die Lokalisierung des myokardialen Ursprungs der VES basiert im Wesentlichen auf der Analyse des QRS-Komplexes im 12 Kanal-EKG. Die Entscheidung zur Therapie von VES ist primär bedingt durch die Symptomatik des Patienten, die VES-Last im 24-h-Langzeit-EKG in Kombination mit der systolischen Funktion des linken/rechten Ventrikels bzw. der vorliegenden strukturellen Herzerkrankung. Die medikamentöse Therapie kann erwogen werden, in der Regel ist die Katheterablation aber effektiver und für den Patienten bei geringem Risiko angenehmer und effizienter.

: Ventricular tachycardia (VT) is a leading cause of cardiovascular death and remains the main cause of sudden cardiac death. Implanted cardiac defibrillators (ICD) improve survival but the recurrent ICD therapies, mostly ICD shocks, are associated with an increased mortality and deleterious psychological effects. In this regard and based on the results of multicenter studies, the current European guidelines recommend early referral for catheter ablation. The ablation strategy (isolated endocardial approach or combined epi-/endocardial) depends mostly on the underlying myocardial disease. Thus, almost all patients with right ventricular dysplasia and Chagas disease, the majority of those with dilative cardiomyopathy, and some patients with ischemic cardiomyopathy (mostly posterior wall infarction or large transmural anterior wall infarction) have an epicardial scar as the underlying substrate for recurrent VT episodes. Thus, in this group of patients, isolated endocardial VT ablation may be associated with an increased VT recurrence and therefore an epicardial approach is also needed. Cardiac imaging (cardio-CT/MRI with late enhancement[MRI LE]) can reliably identify the distribution and characteristics of the myocardial scar and may be helpful in planning the ablation strategy. When performed in highly specialized centers, epicardial catheter ablation of VT leads to a significant reduction of recurrent VT episodes compared to the endocardial VT ablation alone and with lower complication rates.

Ventrikuläre Tachykardien sind eine der führenden Ursachen kardialer Mortalität und bleiben die Hauptursache des plötzlichen Herztodes. Implantierbare Kardioverter-Defibrillatoren (ICD) verbessern die Überlebensprognose, aber wiederholte Therapieabgaben (v. a. ICD-Shocks) führen zu einer erhöhten Mortalität sowie zu psychologischer Beeinträchtigung. In dieser Hinsicht und basierend auf Ergebnissen multizentrischer Studien empfehlen die aktuellen europäischen Leitlinien eine frühzeitige Katheterablation bei Patienten mit rezidivierenden, anhaltenden und therapiebedürftigen VT-Episoden bei ischämischer Kardiomyopathie. Die Ablationsstrategie (isoliert endokardial oder kombiniert epi-/endokardial) hängt von dem vorliegenden strukturellen myokardialen Erkrankung ab. Fast alle Patienten mit arrhythmogener Dysplasie des rechten Ventrikels, Patienten mit Morbus Chagas sowie über 40 % der Patienten mit nichtischämischer dilatativer Kardiomyopathie (NIDCM) und einige der Patienten mit ischämischer Kardiomyopathie (v. a. bei Z. n. Hinterwandinfarkt oder großen transmuralen Vorderwandinfarkten) weisen ein epikardiales Substrat auf. Bei dieser Patientengruppe kann die isolierte endokardiale Ablation mit einem erhöhten Rezidivrisiko assoziiert und somit eine epikardiale VT-Ablation notwendig sein. Die kardiale Bildgebung (Kardio-CT/MRT) kann zuverlässig die Narbenverteilung sowie die Eigenschaften der myokardialen Vernarbung einschließlich einer möglichen epikardialen Beteiligung darstellen und somit für die Planung der Ablationsstrategie hilfreich sein. Eine epikardiale VT-Ablation sollte in spezialisierten Zentren erfolgen, da unter diesen Bedingungen die Ablation sicher und höchst effektiv durchgeführt werden kann.