Abstract Introduction Despite technical progress and numerous approaches in ablation strategies, long-term success in paroxysmal atrial fibrillation (PAF) treatment is still suboptimal. Non-transmural ablation lesions in antral isolation lines, causing late electrical reconnection between pulmonary veins (PVs) and left atrium (LA) could present one of the potenital issues for reduced effectiveness of radiofrequency cathether ablation (RFCA). Potentially, these lesions can be identified with high-density (HD) mapping as low voltage, fragmented electrocardiograms (LFEGMs) representing gaps in antral isolation lines. Purpose To compare the long-term pulmonary vein isolation (PVI) durability of two PVI verification methods (circumferential vs high-density mapping catheter) after catheter ablation of PAF. Methods Thirty-three patients with PAF were prospectively randomized to PVI verification by either circumferential mapping catheter (CM group) or HD mapping catheter (HD group). Patients in both groups underwent PVI according to the CLOSE protocol with PVI verification after a 30 minute waiting period. Additionally, in the HD group antral ablation lines were mapped to search for LFEGMs that were defined as fragmented signals (at least 3 deflections) and/or conduction to the LA during stimulation on the ablation line (10 mA at 1 msec) and/or voltage amplitude above 0.1 mV. If LFEGMs were found, additional ablations were performed until electrical inactivity was confirmed with the HD catheter. To monitor AF reccurence 6-day continuous holter ECG was performed after 3, 6, and 12 months after the initial procedure. Arrhythmia recurrence was defined as any atrial tachyarrhythmia lasting more than 30 seconds. Patients also underwent a mandatory second procedure 12 months after the initial PVI, during which HD re-mapping was performed to test durability of PVI and absence of conducting gaps in antral isolation lines. Results There were 16 patients in the CM group and 17 patients in the HD group. Baseline characteristics (gender, age, body mass index, LA volume index, left ventricular ejection fraction, CHA2DS2VASc score) did not significantly differ between the groups. Procedural characteristic are summarized in Table 1. There were significantly more isolated PVs at the remapping procedure in the HD group compared to the CM group (91.2% (62/68) vs 75.0% (48/64); P=0.021). There were also significantly more patients with all PVs durably isolated in the HD group (82.4% (14/17) vs 37.5% (6/16); P=0.008). However, arrhythmia recurrence rate was similiar between the CM and HD group (43.8% (7/16) vs 35.3% (6/17); P=0.640). Conclusion HD mapping improved PVI durability after 12 months compared to standard CM verification. However, lower number of isolated PVs in the HD group did not have an impact on arrhythmia reccurence.

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Intracardiac echocardiography (ICE) is gaining increasingly wider adoption in interventional electrophysiology (EP) and represents an all-round tool for ablation of atrial fibrillation (AF). The key upgrade to the usefulness of ICE is its integration into three-dimensional (3D) electroanatomic mapping (EAM) system (ICE/EAM automatic integration system). Purpose The aim of this single-centre retrospective study was to evaluate feasibility, safety and acute efficacy of ICE/EAM automatic integration system guided fluoroless ablation of AF. Methods Patients with symptomatic paroxysmal or persistent AF referred for first pulmonary vein isolation (PVI) radiofrequency catheter ablation (RFCA) from September 2017 to August 2020 were included in the study. Those who underwent additional ablations for concomitant arrhythmias were excluded from statistical analysis. All procedures were performed without the use of fluoroscopy. A detailed 3D virtual anatomy of the left atrium (LA) and structures relevant to AF ablation was constructed from ultrasound contours obtained with ICE probe inside the LA. Pulmonary veins (PVs) and antral regions were additionally mapped with fast anatomical mapping. PVI was performed with contact force (CF) sensing catheter. Procedural endpoint was successful PVI. Results A total of 56 patients underwent RFCA (35.7% females, median age 62.7 years, 53.6% paroxysmal AF). Acute PVI was achieved in all patients (100%). Adverse events were detected in two patients (3.6%). The median procedure duration was 110.5 min (IQR 100.0-133.8). First-pass isolation was achieved in 50/56 LPVs (89.3%) and in 44/56 RPVs (78.6%). In patients where first-pass isolation was no achieved, intravenous carina had to be ablated in 3/6 (50%) of LPVs and 9/12 (75%) of RPVs. Conclusions Flouroless PVI using ICE/EAM automatic integration system is feasible, safe and acutely effective. We achieved high rate of first-pass isolation.

Abstract Background Transseptal puncture (TSP) for catheter ablation (CA) of left-sided tachycardias is traditionally performed with the aid of fluoroscopy. Compared to fluoroscopy, intracardiac echocardiography (ICE) can provide better orientation and imaging of soft tissue structures that are relevant to TSP. Objective Our aim was to evaluate feasibility and safety of ICE-guided TSP in CA treatment of left-sided tachyarrhythmias. Methods Consecutive fluoroless CA procedures with combined use of three-dimensional electroanatomic mapping system and ICE requiring TSP were evaluated in 357 patients (269 male, mean age 54 ± 18 years) referred to our hospital from July 2014 to November 2018. Among CA treated left-sided tachyarrhythmias 55 patients had accessory pathway, 16 had focal atrial tachycardia, 276 had atrial fibrillation or atypical atrial flutter and 10 had ventricular tachycardia. Success of transseptal access and complications related to TSP were analyzed. Adverse event requiring additional intervention was defined as major complication. Results Double TSPs were performed in 253 patients and single in 104 patients. Additional ablation procedures were needed in 26 patients and the rest had a single CA procedure. Altogether, 661 TSPs (274 double and 111 single) were attempted and 659 were successful (99.7%). Both TSPs failed due to severely thickened interatrial septum after previous cardiac surgery. In 14 patients (21 TSPs, 3.2%) a cardiac implantable electronic device (CEID) was present. ICE provided excellent lead visualisation and no lead dislodgements were recorded. Additional radiofrequency energy application to the transseptal needle was used for 3 challenging TSPs. Minor complications (pericardial effusions managed conservatively) occurred after 7 double TSP procedures (12/661, 1.8%). Major complication with pericardial tamponade (requiring pericardiocentesis) occurred during one double TSP (2/661, 0.3%). No TSP-related embolic complications were observed. Conclusion ICE-guided TSP in CA of left-sided tachyarrhythmias is safe with excellent success rates. In addition, ICE could provide additional reassurance in difficult cases and in patients with CEIDs.

Abstract Introduction The clinical presentation of cardiac sarcoidosis (CS) ranges from an incidentally discovered condition to heart failure with risk of sudden cardiac death (SCD). As there is no single reliable test for detecting CS, noninvasive multimodality imaging plays a crucial role in establishing the diagnosis and SCD risk-stratification. We present a case of a young patient diagnosed with CS in whom, on the basis of multiple imaging results, dual-chamber ICD for primary prevention was implanted outside practice guidelines. Case A 37-year-old woman was admitted to our hospital due to occasional palpitations and incidentally recorded nonsustained monomorphic ventricular tachycardia (VT). One year ago she was diagnosed with pulmonary sarcoidosis and was put on methylprednisolone; ECG, 24-h Holter monitoring and echocardiogram were normal. In the present admission control echocardiogram, with the exception of decreased longitudinal deformation of the basal and mid segments of the infero- and anterolateral left ventricle (LV) wall, was unremarkable. However, cardiac magnetic resonance (CMR) showed sub-epicardial late gadolinium enhancement (LGE) along the lower third of the antero- and inferolateral LV free wall and in the apical lateral segment of LV. Apart from some focal metabolically active lesions in the lungs and liver, fluorodeoxyglucose positron emission tomography with computed tomography (FDG PET/CT) displayed increased metabolic activity in the apical half of the antero- and infero-lateral segments of the LV. On the basis of this results CS was confirmed. Given the age, reduced longitudinal strain, notable LV LGE presence and increased cardiac metabolic activity, dual-chamber ICD to prevent SCD and possible bradycardia risk was implanted. The patient continued with immunosupressive therapy; 8 mg of methylprednisolone every other day. Conclusion In our case, integrated multimodality imaging played a crucial role in establishing CS diagnosis and SCD risk stratification. A comprehensive evaluation of patients with CS is vital for making the best clinical decisions.