Background Clinical radiation audits are useful to reduce ionizing radiation in clinical practice. The first Swiss radiation audit in Cardiology took place at the University Heart Center Zurich in 2019. Objectives To compare local diagnostic reference levels (DRLs) in cardiac electrophysiology (EP) procedures to the currently available national DRLs and to examine patient radiation exposure before and after the clinical radiation audit. Methods Retrospective study including 775 patients undergoing EP procedures from 2018- 2020. Main recommendations of the clinical audit were the regular use of collimation, semitransparent filters, the reduction of cine images and frame rates. Patient radiation exposure was evaluated with cumulative doses, fluoroscopy times and dose-area product (DAP). Secondary endpoints were acute procedural success rates and 30-day complications. Results 447 (57.5%) patients prior to, and 328 (42.3%) after the audit were included. Cryoballoon pulmonary vein isolation (PVI) was performed in 14.1%, PVI radiofrequency (RF) ablation in 26.8%, RF ablation of right-sided supraventricular tachycardia in 32.1%, other procedures in 27% of cases. Local DRLs for the DAP were below national DRLs (1 Gy cm2 vs 150 Gy cm2 for AVNRT/AVRT ablation). After the audit, there was a significant radiation reduction for right-sided supraventricular tachycardia ablation (cumulative dose: 4.8 mGy vs 2.1 mGy and fluoroscopy times: 210 seconds vs 107 seconds, p < 0.001) and PVI with RF (50.4 mGy vs 29.5 mGy, and 378 seconds vs 191 seconds, p < 0.003; respectively). No significant differences were found in acute procedural success rates or 30-day complications. Conclusions The clinical radiation audit was associated with a significant reduction of patient radiation exposure for right-sided supraventricular tachycardia ablation and PVI with RF.

AIM: To establish local diagnostic reference levels for cardiac implantable electronic device procedures and to compare local practice with national guidelines. METHODS: A retrospective cohort study including all consecutive patients from October 2018 to October 2020 who underwent implantation of a cardiac implantable electronic device including pacemaker, implantable cardioverter defibrillator (ICD), cardiac resynchronisation therapy (CRT) or lead extraction / device explantation. Data was collected from a dose management system and cross-checked for accuracy with the patient information system. The pre-specified outcome was patient radiation exposure, evaluated with the kerma area product (KAP), cumulative dose, fluoroscopy time and number of cine acquisitions. The median values were set as local diagnostic reference levels. RESULTS: A total of 541 patients were included. 28.3% had a conventional pacemaker, 22.0% a leadless pacemaker, 21.1% an ICD and 17.2% a CRT implanted, while lead extraction / device explantation was performed in 11.5% of patients. The local diagnostic reference levels for the kerma area product were lower than the national Swiss diagnostic reference levels (0.4 Gray [Gy]∙cm2 vs 30 Gy∙cm2 for conventional pacemakers; 0.4 Gy∙cm2 vs 20 Gy∙cm2 for ICDs; 10.2 Gy∙cm2 vs 57 Gy cm2 for CRTs). Similarly, the local diagnostic reference levels for cumulative dose and fluoroscopy time were below national diagnostic reference levels. CONCLUSIONS: Local diagnostic reference levels values were far below national diagnostic reference levels. A multicentre approach to assess patient radiation exposure in current practice is strongly desired to establish revised national diagnostic reference levels.

Background Arrhythmogenic right ventricular cardiomyopathy (ARVC) presents diagnostic challenges and significant clinical burden because of life-threatening ventricular arrhythmias, compounded by the limited ability to predict patient prognosis using current clinical parameters. MicroRNAs (miRNAs) offer potential as markers in cardiac diseases, including ARVC, providing insights into disease pathogenesis, identification, and prognosis. However, current diagnostic criteria lack sensitivity and specificity, highlighting the need for novel markers such as miRNAs to better understand ARVC's complex pathophysiologic mechanisms. Objective This multisite study assessed circulating miRNA expression in ARVC patients, stratified by 5-year event-free survival risk, to explore their potential as a marker for improving ARVC diagnosis and prognosis. Methods Blood samples from 102 ARVC patients, 24 Brugada syndrome (BrS) patients, and 22 healthy controls were analyzed for the expression of 20 miRNAs using TaqMan quantitative real-time polymerase chain reaction (PCR), ARVC patients were stratified by 5-year event-free survival risk. Six candidate miRNAs were selected for further analysis, and machine learning algorithms were applied for classification and risk stratification based on miRNA profiles. Additionally, genotyping and functional annotation of miRNA targets were performed. Results Six miRNAs exhibited differential expression between high- and low-risk ARVC patients. MiR-15a-5p, miR-16-5p, and miR-92a-3p demonstrated the best performance in risk stratification. MiR-15a-5p also displayed higher expression in patients with adverse cardiac events. Comparative analysis with BrS patients and healthy controls consistently demonstrated increased expression of these miRNAs in ARVC. Conclusion This study highlights miRNAs’ potential to enhance the diagnosis, disease progression, and clinical outcomes of ARVC, supporting further research to improve patient care.

BACKGROUND:Genetic variants in desmosomal cadherins, desmoglein 2 (DSG2) and desmocollin 2 (DSC2), cause a distinct form of arrhythmogenic right ventricular cardiomyopathy (ARVC), which remains poorly reported. In this study, we aimed to provide a comprehensive description of the phenotypic expression, natural history, and clinical outcomes of patients with this ARVC subset. METHODS:Genetic and clinical data of DSG2 and DSC2 variant carriers were collected from 5 countries in Europe and Asia. We assessed the phenotypic profile of these patients and their clinical outcomes, focusing on heart failure and ventricular arrhythmia events. RESULTS:Overall, 271 subjects, 254 with DSG2 variants, were included in this study (median age, 38 years [interquartile range, 25-52]; 62.7% male). Of these, 165 were probands, and 200 were diagnosed with definite ARVC. A total of 181 (66.8%) individuals carried missense variants, mainly distributed in the extracellular domains. Notably, we included 78 (28.8%) individuals with multiple variants. Of the 200 cases with diagnosed ARVC, 41 (20.5%) experienced premature cardiac death before the age of 65. Among the 81 individuals for whom both left ventricular ejection fraction and right ventricular fractional area change data were available at presentation, 29 (35.8%) had isolated right ventricular dysfunction, and 16 (19.8%) had biventricular dysfunction. Single-variant carriers who engaged in intense physical exercise were younger at disease onset compared with those who did not (P=0.001). Compared with single-variant carriers, those with multiple variants were more likely to be diagnosed with ARVC (96.2% versus 64.8%; P<0.001) and exhibited more severe left ventricular dysfunction (44.4% versus 22.1%; P=0.001) and right ventricular dilation (88.9% versus 55.8%, P<0.001). Multiple-variant carriers were significantly younger at ARVC diagnosis compared with single-variant carriers (33 [18-49] years versus 42 [27-54] years; P<0.001]. During follow-up, end-stage heart failure (P<0.001) and malignant ventricular arrhythmias (P=0.004) were significantly more frequent in multiple-variant compared with single-variant carriers. Compared with PKP2 patients, DSG2/DSC2 patients exhibited a significantly higher risk of end-stage heart failure (P<0.001). CONCLUSIONS:ARVC attributable to variants in desmosomal cadherins mostly present with right ventricular or biventricular disease. Multiple variants are common in these patients and are associated with more frequent clinical penetrance, earlier onset of disease, and adverse clinical outcomes.

Introduction Intense endurance exercise is discouraged for patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), as it can increase the risk for adverse cardiac events as well as accelerate disease progression. While a sedentary lifestyle is also not advisable, there is currently no prospective data on the safety of physical activity for ARVC patients. To describe ARVC patients' average and peak ventricular arrhythmia burden – estimated from the prevalence of premature ventricular contractions (PVC) – measured during and after different exercise modalities and intensities, in context with cardiac and physiological load. Methods Twenty ARVC patients (8 f/12 m, age 48 ± 15 years, BMI 24 ± 3 kg/m2, resting PVC burden 4 ± 4%) with a heterozygous pathogenic/likely pathogenic plakophilin-2 (PKP-2) variant prospectively performed different exercises while monitored via 12-lead ECG. The order of modalities was randomized and participants were instructed to stop when surpassing perceived exertion of 15 (6-20 Borg scale). Resistance exercises included 2-min two-legged squats and single arm biceps curls (20 repetitions each) while endurance exercise included 5-min treadmill walking at comfortable speed and 3-min cycling bouts at a heart rate (HR) of 80, 100 and 120 bpm. Each activity was followed by a 10-min recovery period. Blood lactate concentration [La-] was assessed at the end of each cycling bout, with 4 mmol/L defined as a threshold to describe high-intensity exercise. Results No adverse events (including sustained ventricular tachyarrhythmia) nor premature terminations occurred. Average PVC burden during activities (including 5 min recovery) was lower for biceps curls compared with all other activities (p < 0.046), despite having the second highest level of perceived effort (13.8 ± 1.7 units). Biceps curls elicited ~20 mmHg (p < 0.001) lower peak systolic blood pressure and ~40 bpm peak lower HR (p < 0.001) compared with cycling at 120 bpm, despite similar perception of effort (12.9 ± 1.7, p = 0.818). Peak PVC burden during the different activities (highest PVC count in 1 min) ranged between 0–57% among participants and it was lower during the activities (5 ± 8%) than the subsequent 5-min recovery (8 ± 8%, p = 0.006). but no differences were detected between activities. Five patients (25%) presented [La-] that exceeded 4.0 mmol/L when cycling at 120 bpm. Discussion/Conclusion PVC burden, a marker for arrhythmogenicity, was generally higher during recovery than during exercise, with the smallest burden found during the exercise with a small muscle mass, despite high perceived exertion. Thus, such exercises might be better suited for training in ARVC patients. Generalized recommendations for a maximum HR of 120 bpm during exercise likely predispose a high number of ARVC patients to inadvertently perform high-intensity exercise, risking accelerating disease progression. Therefore, individualized exercise prescription should be recommended.

This study aimed to assess the feasibility of left ventricular myocardial characterization in patients with ventricular arrhythmias using late enhancement (LE) photon-counting detector computed tomography (PCD-CT) scans, in comparison with invasive endocardial electroanatomical mapping (EAM). This single-center retrospective observational study included 20 patients (mean age 64 ± 8 years, 4 female) who underwent PCD-CT prior to 3D endocardial uni- and bipolar EAM and radiofrequency catheter ablation (RFCA) between May 2022 and February 2024. Sixteen patients (80

Characterization of the myocardial substrate by non-invasive imaging has been proven useful to guide invasive 3D electroanatomical mapping (EAM) and catheter ablation (CA) of ventricular arrhythmias (VA) in patients with structural heart disease. Cardiac magnetic resonance tomography is considered as the current gold standard for pre-procedural non-invasive delineation of the myocardial substrate, but is limited by incompatible cardiac implantable electronic devices (CIED), imaging artefacts in CIED patients and claustrophobia. To assess the utility of photon counting detector computed tomography (PCD-CT), a novel and rapid non-invasive imaging tool, for myocardial substrate delineation and its correlation with invasive 3D EAM. This single-center retrospective observational study included 20 patients (12 [60%] with ischemic and 8 [40%] with non-ischemic cardiomyopathies), who underwent pre-procedural PCD-CT and 3D EAM-guided radiofrequency CA of VA between May 2022 and February 2024. Cardiac PCD-CT scans included angiographic and late enhancement (LE) acquisitions 5 minutes after contrast injection in the ECG-gated sequential mode. Endocardial 3D uni- and bipolar EAM of the left ventricle were performed with a multipolar mapping (Pentaray) and focal radiofrequency ablation (Thermocool) catheter using CARTO V3 (all Biosense Webster). Low voltage areas were defined as <5 mV in unipolar and <0.5 mV in bipolar maps. Myocardial segments with scars identified on polar and atlas maps from cardiac LE scans were compared with low voltage areas on invasive 3D EAM, and concordance of pathologic segments was calculated per patient between both modalities. Mean age was 64±8 years, 4 patients (20%) were female and CIEDs were present in 14 patients (70%). In patients with ischemic cardiomyopathy, unipolar and bipolar EAM identified 9±3 and 8±3 low voltage segments, and in patients with non-ischemic cardiomyopathy, 9±6 and 4±2segments, respectively. In patients with ischemic cardiomyopathy concordance between cardiac LE scans and unipolar EAM was high (defined as >75% concordance of segments) in 10 (83%) patients and moderate (defined as 50-75%) in 2 (17%) patients; concordance between cardiac LE scans and bipolar EAM was high in 7 (59%) and moderate in 5 (41%) patients. In patients with non-ischemic cardiomyopathy concordance was high in 5 (63%), moderate in 2 (25%) patients and low (defined as 25-50% concordance of segments) in 1 patient (12%) for unipolar EAM, whereas concordance was high in 2 (25%), moderate in 4 (50%), and low in 2 patients (25%) for bipolar EAM. Myocardial substrate characterization with cardiac PCD-CT yields a strong concordance with left ventricular unipolar EAM, particularly in patients with ischemic heart disease, and may constitute an alternative for pre-procedural imaging in patients referred for CA of VA.

The interpretation of the surface electrocardiogram and intracardiac recordings is key for the appropriate diagnosis and interventional treatment of cardiac arrhythmias.This report describes a patient with both a focal atrial tachycardia (AT) and an atypical atrioventricular-nodal reentrant tachycardia that were repeatedly induced and terminated by atrial ectopic beats.Radiofrequency ablation of the slow pathway, as well as targeted ablation of the specific AT focus effectively eliminated both tachycardias.

Abstract Background Substrate-based ablation has emerged as a successful technique for VT ablation, especially in patients with ischemic cardiomyopathy with markedly reduced left ventricular function. High-density mapping catheters provide high-resolution electroanatomical maps and better discrimination of abnormal substrates and local activation in the heart chambers, making them a valuable and safe resource in the electrophysiology laboratory. Purpose The purpose of this study was to investigate differences in procedural characteristics and clinical outcomes of VT ablation with ischemic cardiomyopathy. VT ablations were guided by two mapping strategies: high-density mapping using a high-density mapping catheter and conventional mapping using an ablation catheter. Methods Patients with ischemic cardiomyopathy receiving VT ablation at our center between January 2018 and June 2023 were retrospectively included. Procedural characteristics and clinical outcomes were compared between patients receiving high-density mapping with a multielectrode-mapping catheter vs conventional mapping with a single-tip irrigated ablation catheter. Results Eighty-four patients with ischemic cardiomyopathy who underwent VT ablation were consecutively included (mean age 67 ± 12 years, mean LVEF 32 ± 11 %, 79 (94%) males). Fifty-seven (68 %) procedures were performed using high-density mapping, and 27 (32 %) conventional mapping. In the high-density mapping and conventional mapping group, the total procedure time was 256 ± 77 min vs. 232 ± 61 min (P < 0.05) and the total fluoroscopic dose was 1643 ± 204 μGy.m2 vs. 948 ± 105 μGy.m2 (P < 0.05), respectively,. However, there was no difference between the two groups in terms of acute success (84% vs 80%, P > 0.05) or major complications (5% vs 4%, P > 0.05). The mean duration of follow-up was 2.6 years (4 - 51 months). The 1-year mortality rates were 4% vs 7% in the high-density mapping and conventional mapping groups, respectively (P < 0.05). The 3-month and 1-year single-procedural sustained VT/VF-free rates were 77% vs 59% and 74% vs 63%, respectively (P < 0.05). The 1-year incidence of sustained VT/VF recurrence was 7.0 per 100 person-years in high-density mapping group, compared with 7.4 per 100 person-years in the conventional group. Conclusions VT ablation in patients with ischemic cardiomyopathy using high-density mapping appears to be superior to conventional mapping in terms of reducing postprocedural VT/VF recurrence and a subsequent reduction of overall mortality.Figure 1Figure 2

Abstract Background Arrhythmogenic left ventricular cardiomyopathy (ALVC) as a subtype of arrhythmogenic cardiomyopathy (ACM) is increasingly being recognized. Cardiac magnetic resonance (CMR) has emerged as the primary imaging modality for the diagnosis of ACM. In patients with right-dominant ACM (ARVC) and recurrent sustained ventricular tachycardia (VT), endocardial +/-epicardial ablation yields good clinical outcomes in the long-term. However, studies on VT ablation in ACM with LV involvement are scarce. Purpose We sought to investigate clinical outcomes of VT ablation in ACM patients with LV involvement. Methods The study included patients from the Zurich ACM Registry who met 2020 "Padua Criteria" for ACM and underwent VT ablation between January 2018 and July 2023. Epicardial ablation was performed in patients with recurrent sustained VT despite endocardial ablation, those lacking and endocardial substrate or if the ECG of the VT / substrate on CMR was suggestive of an epicardial origin. Catheter ablation was guided by activation/entrainment mapping for mappable VT, and pace mapping/voltage mapping during sinus rhythm for unmappable VT. Consecutive follow-up of all patients was performed according to our protocol. Results Twenty-one ACM patients underwent n=24 VT ablation procedures. Of those 20 patients, 6 patients (30%) had LV involvement on CMR. Eight (33%) patients underwent epicardial +/- endocardial ablation. Among patients receiving epicardial ablation, 3 patients (38%) had LV involvement. These three underwent a single ablation procedure, which was epicardial only. Total follow-up was 30 months (range 4-43). Three-month sustained VT/VF recurrence rates were 12% in the ACM group with LV involvement vs 25% in ACM without LV involvement. All patients with sustained VT/VF recurrence underwent repeat ablation via an epicardial approach within 3 months and were free of sustained VT/VF thereafter during a median follow-up of 12 months. One-year recurrence rate did not differ between ACM patients with LV involvement vs. without LV involvement (7.7% vs 8.3%, P＝0.117). Seven out of eight epicardial ablations achieved freedom from VT/VF after one-year follow-up. One ARVC patient with previous endocardial ablation had recurrent VT one month after epicardial ablation, which was free of VT after Flecainide combined with beta-blocker. No significant differences were found in the use of beta-blockers and antiarrhythmic drugs between both groups (ACM with LV involvement vs. without LV involvement) at baseline and during one-year follow-up. Conclusions Single or adjuvant epicardial substrate ablation of VT in arrhythmogenic cardiomyopathy is promising in terms of postprocedural VT free survival, especially in patients with left ventricular involvement demonstrated by CMR.Figure 1Figure 2

BACKGROUND:Atrial fibrillation is the most commonly observed cardiac rhythm disorder. Pulmonary vein isolation (PVI) is an effective treatment option to maintain sinus rhythm. This study evaluates the safety, efficacy, clinical outcomes and radiation exposures using a standardized single transseptal puncture (STP)-strategy. METHODS:We analyzed data from patients who underwent our STP-ablation technique with transesophageal echocardiography (TEE) guidance at a university hospital and a regional tertiary health center in Switzerland between January 1, 2017, and May 30, 2022. Collected data included demographics, symptoms, echocardiography results, procedural details, complications and outcomes. Mean follow-up time was 21.4 ± 16 months. RESULTS:The study population included 304 patients with a median age of 67 years, who had at least one ablation using our STP-approach. Among these, 248 (82 %) patients underwent de novo PVI with this technique. Ablation was successful in all patients with isolation of all pulmonary veins, with an average procedure duration of 120 min and an average fluoroscopy time of 3 min, resulting in a mean X-ray dose of 252 cGy × cm2. TEE guidance was performed in 235 (95 %) patients. During the first intervention, 17 complications occurred in 13 patients (5 %). After the first PVI, 135 (54 %) patients experienced no recurrence during the follow-up period. The one-year recurrence rate for atrial fibrillation requiring therapy was 30 %. CONCLUSION:Our STP- approach demonstrated comparable success rates to traditional methods, with similar procedural durations, low radiation exposure and a low complication rate. Therefore, this method may offer procedural, economic and safety benefits without compromising efficacy or safety.

Aims: Although the application of ultrasound-guided vascular puncture and Z-stitch hemostasis to manage femoral access has been widely utilized, there is limited data on this combined application in adult congenital heart disease (ACHD) patients undergoing electrophysiological (EP) procedures.We sought to evaluate the safety and efficacy of ultrasound-guided puncture and postprocedural Z-stitch hemostasis for ACHD patients undergoing EP procedures.Methods and Results: The population of ACHD patients undergoing transfemoral EP procedures at the University of Zurich Heart Center between January 2019 and December 2022 was observed and analyzed.During the study period, femoral access (left/right, arterial/venous) was performed under real-time ultrasound guidance.At the end of the procedure, a single Z-stitch was performed at the puncture site.We evaluated the incidence of in-hospital complications associated with femoral access puncture in this population.Among 101 patients who had a total of 147 previous ipsilateral vascular punctures (mean 1.5 per person), 100 patients underwent successful femoral vascular access for EP procedures.The median age of the patients was 47 ± 15 years and 34 (34%) were male.Z-stitches were performed after the procedure in 100 patients with 303 femoral vascular accesses (mean 3 punctures per person).No patient developed vascular puncture relevant inguinal hematoma, pseudo aneurysm, arteriovenous fistula, venous or arterial thrombosis.Conclusion: In ACHD patients undergoing EP procedures, optimal femoral access management can be achieved with ultrasound-guided puncture and postprocedural Z-stitch hemostasis.

Abstract Background Clinical audits aim to ensure ideal use of ionizing radiation in clinical practice. Since it became mandatory by Swiss law in 2018, such an audit also took place in our Cardiac Pacing and Electrophysiology Division at the University Heart Center. Purpose To establish local diagnostic reference levels (DRLs) for specific procedures and to examine if patient radiation exposure was reduced after the clinical audit. Methods Retrospective cohort study including patients from October 2018 to October 2020 who underwent device implantation, including pacemakers, implantable cardioverter defibrillators (ICD), cardiac resynchronization therapy (CRT), or lead extraction / device explantation. Main measures to reduce radiation exposure after the audit were lower pulsed fluoroscopy frame rates and dose characteristics at baseline. Patient radiation exposure was evaluated with the dose-area product (DAP), cumulative dose, fluoroscopy time, and the number of cine acquisitions. Secondary endpoints included the effective dose, the acute procedural success rate and 30-day complications. Data were collected from a dose management system and cross-checked for accuracy with the patient information system. The third quartiles were set as local DRLs. Data before and after the clinical audit were compared. Results A total of 541 patients (45.7 % before the audit, 54.3% after the audit) were included. 28.3% had a conventional pacemaker, 22.0% a leadless pacemaker, 21.1% an ICD, and 17.2% a CRT implantation. Lead extraction / device explantation was undergone by 11.5% of patients. The local DRLs (including all procedures before and after the audit) for the DAP were significantly lower as compared to national DRLs (6.2 dGy.cm2 versus 300 dGy.cm2 for conventional pacemakers; 7.6 dGy.cm2 versus 200 dGy.cm2 for ICDs, 203 dGy.cm2 versus 570 dGy.cm2 for CRTs). After the audit, DAP (Figure 1), cumulative dose, effective dose and the number of cine acquisition significantly decreased for conventional pacemakers (p-value ≤ 0.04), whereas no significant differences were observed for the other procedures. The acute procedural success rate (98.4 vs 98.9%) and the 30-day complications (4.0 vs 7.8%) were not significantly different before and after the audit. Conclusions The clinical audit in our institution led to a significant reduction of radiation exposure for patients during pacemaker implantations. Regarding DRLs, local values were far below national DRLs, which suggests that national DRLs need to be updated more regularly. Our study highlights the importance of clinical audits and the need for more research in this field.

AimTo investigate the clinical significance of right atrial mapping prior to cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL).MethodsClinical and ablation parameters were retrospectively assessed and compared in patients undergoing CTI ablation with or without a first-step right atrial mapping (FRAM) by using the CARTO 3D mapping system.ResultsCTI block by radiofrequency ablation (RFA) was achieved in all 143 patients. In the FRAM group there was a shorter ablation duration and fluoroscopy exposure compared with the non-FRAM group. CHA2DS2-VASc score was associated with higher ablation durations, more ablation applications and increased fluoroscopy exposure. Body mass index (BMI) was associated with longer ablation duration and more ablation applications. Furthermore, patients with reduced left ventricular ejection fraction (LVEF) had longer ablation durations and more fluoroscopy exposure. One patient in the non-FRAM group developed cardiac effusion after ablation. None of the patients had recurrence after 6 months of follow-up.ConclusionsPatients with high BMI, high CHA2DS2-VASc score and reduced LVEF may benefit from the FRAM approach by reducing ablation duration, number of ablation applications and fluoroscopy exposure.

BackgroundData on the incidence of arrhythmias, associated cardiac interventions, and outcome in patients with dextro-transposition of the great arteries and atrial switch are scarce. Methods and ResultsIn this multicenter analysis, we included adult patients with dextro-transposition of the great arteries and atrial switch regularly followed up at 3 Swiss tertiary care hospitals. The primary outcome was a composite of left ventricular assist device, heart transplantation, and death. The secondary outcome was occurrence of ventricular tachycardia, ventricular fibrillation, or sudden cardiac death. We identified 207 patients (34% women; median age at last follow-up, 35 years) with dextro-transposition of the great arteries and atrial switch. Arrhythmias occurred in 97 patients (47%) at a median age of 22 years. A pacemaker or an implantable cardioverter-defibrillator was implanted in 39 (19%) and 13 (6%) patients, respectively, and 33 (16%) patients underwent a total of 51 ablation procedures to target 60 intra-atrial re-entry tachycardias, 4 atrioventricular nodal re-entry tachycardias, and 1 atrial fibrillation. The primary outcome occurred in 21 patients (10%), and the secondary outcome occurred in 18 patients (9%); both were more common in patients with concomitant ventricular septum defect than in those without (hazard ratio [HR], 3.06 [95% CI, 1.29-7.27], P=0.011; and HR, 3.62 [95% CI, 1.43-9.18], P=0.007, respectively). ConclusionsIn patients with dextro-transposition of the great arteries and atrial switch reaching adulthood, arrhythmias occur in almost half of patients, and associated rhythm interventions are frequent. One-tenth of those patients do not survive until the age of 35 years free from left ventricular assist device or heart transplantation, and the outcome is worse in patients with concomitant ventricular septum defect.

AIMS:The widespread use of three-dimensional (3D) mapping systems and echocardiography in the field of cardiac electrophysiology has made it possible to perform transseptal punctures (TSP) with low or no fluoroscopy. However, such attempts in adults with congenital heart disease (ACHD) who have previously undergone surgical or interventional treatment are limited. Therefore, we sought to explore the feasibility and safety of an approach to perform zero- or low-fluoroscopy TSP in ACHD patients undergoing left atrial cardiac ablation procedures.METHODS AND RESULTS:This study included 45 ACHD patients who underwent TSP for ablation of left-sided tachycardias (left atrium or pulmonary venous atrium). Computed tomography (CT) of the heart was performed in all patients prior to ablation. 3D mapping of the right-sided heart chambers before TSP was used to superimpose the registered anatomy, which was subsequently used for the mapping-guided TSP technique. TSP was performed with zero-fluoroscopy in 27 patients, and the remaining 18 patients had a mean fluoroscopy exposure of 315.88 ± 598.43 μGy.m2 and a mean fluoroscopy duration of 1.9 ± 5.4 min. No patient in this cohort experienced TSP-related complications.CONCLUSION:Our study describes a fluoroscopy-free or low-dose fluoroscopy approach for TSP in ACHD patients undergoing catheter ablation of left-sided tachyarrhythmias who had been previously treated surgically or interventionally due to congenital heart defects. By superimposing 3D electroanatomic mapping with cardiac CT anatomy, this protocol proved to be highly effective, feasible and safe.