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Background: Despite the progressive course of atrial fibrillation (AF), the optimal timing of radiofrequency catheter ablation (RFCA) during disease course is still unknown. We aimed to investigate the impact of early RFCA within a year after AF diagnosis on procedural outcomes. Methods: A single-center retrospective study was conducted on symptomatic AF patients (n = 130) referred for RFCA with a 16-month median follow-up. Patients were stratified based on the diagnosis-to-ablation time (DAT) into early (≤1 year) and late (>1 year) RFCA groups. Atrial arrhythmia recurrence after single RFCA was the primary outcome. Secondary outcomes included cardiovascular hospitalizations, AF progression, and antiarrhythmic drug (AAD) use. Results: Within a year of AF diagnosis, 33 patients (25.4%) underwent RFCA. In the early-RFCA group, 84.4% of patients did not have recurrent atrial arrhythmia, in contrast to 60.8% in the late-RFCA group (p = 0.039). Late RFCA (HR = 2.74, 95% CI = 1.062-7.052, p = 0.037) and AF recurrence during the blanking period (HR = 4.57, 95% CI = 2.38-8.57, p < 0.0001) were independent predictors of atrial arrhythmia recurrence on multivariate analysis. Compared to the late-RFCA group, the early-RFCA group had significantly lower rates of cardiovascular hospitalizations (18% vs. 42%, p = 0.023), AF progression (0.0% vs. 11.3%, p = 0.044), and AAD use (45.4% vs. 81.4%, p < 0.001). Conclusions: Early RFCA within a year of AF diagnosis is associated with less atrial arrhythmia recurrence, fewer cardiovascular hospitalizations, less AF progression, and less AAD use. DAT of more than one year and AF recurrence during the blanking period are independent predictors of atrial arrhythmia recurrence after single RFCA.

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Despite progress in implantation technology and prophylactic measures, infection complications related to cardiac implantable electronic devices (CIED) are still a major concern with negative impacts on patient outcomes and the health system's resources. Infective endocarditis (IE) represents one of the most threatening CIED-related infections associated with high mortality rates and requires prompt diagnosis and management. Transvenous lead extraction (TLE), combined with prolonged antibiotic therapy, has been validated as an effective approach to treat patients with CIED-related IE. Though early complete removal is undoubtedly recommended for CIED-related IE or systemic infection, device reimplantation still represents a clinical challenge in these patients at high risk of reinfection, with many gaps in the current knowledge and international guidelines. Based on the available literature data and authors' experience, this review aims to address the practical and clinical considerations regarding CIED reimplantation following lead extraction for related IE, focusing on the reassessment of CIED indication, procedure timing, and the reimplanted CIED type and site. A tailored, multidisciplinary approach involving clinical cardiologists, electrophysiologists, cardiac imaging experts, cardiac surgeons, and infectious disease specialists is crucial to optimize these patients' management and clinical outcomes.

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The right bundle branch (RBB), due to its endocardial course, is susceptible to traumatic block caused by "bumping" during right-heart catheterization. In the era of cardiac electrophysiology, catheter-induced RBB block (CI-RBBB) has become a common phenomenon observed during electrophysiological studies and catheter ablation procedures. While typically transient, it may persist for the entire procedure time. Compared to pre-existing RBBB, the transient nature of CI-RBBB allows for comparative analysis relative to the baseline rhythm. Furthermore, unlike functional RBBB, it occurs at similar heart rates, making the comparison of conduction intervals more reliable. While CI-RBBB can provide valuable diagnostic information in various conditions, it is often overlooked by cardiac electrophysiologists. Though it is usually a benign and self-limiting conduction defect, it may occasionally lead to diagnostic difficulties, pitfalls, or undesired consequences. Avoidance of CI-RBBB is advised in the presence of baseline complete left bundle branch block and when approaching arrhythmic substrates linked to the right His-Purkinje-System, such as fasciculo-ventricular pathways, bundle branch reentry, and right-Purkinje focal ventricular arrhythmias. This article aims to provide a comprehensive practical review of the electrophysiological phenomena related to CI-RBBB and its impact on the intrinsic conduction system and various arrhythmic substrates.

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Catheter ablation (CA) of left atrial tachycardia adjacent to implanted septal closure devices represents a multifaceted challenge. We describe the case of a 57-year-old patient with remote percutaneous closure of atrial septal defect who underwent successful CA of left atrial tachycardia adjacent to the septal device using a transaortic approach and RF energy. Besides the technical difficulties and associated risks, interference between the device and applied RF parameters may limit ablation efficiency. Further research is required to evaluate the safety, efficacy, and optimal energy type/parameters when ablating arrhythmias adjacent to these devices.

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INTRODUCTION: Despite numerous ECG algorithms being developed to localize the site of manifest accessory pathways (AP), they often require stepwise multiple-lead analysis with variable accuracy, limitations, and reproducibility. The study aimed to develop a single-lead ECG algorithm incorporating the P-Delta interval (PDI) as an adjunct criterion to discriminate between right and left manifest AP. METHODS: Consecutive WPW patients undergoing electrophysiological study (EPS) were retrospectively recruited and split into a derivation and validation group (1:1 ratio). Sinus rhythm ECG analysis in lead V1 was performed by three independent investigators blinded to the EPS results. Conventional ECG parameters and PDI were assessed through the global cohort. RESULTS: A total of 140 WPW patients were included (70 for each group). A score-based, single-lead ECG algorithm was developed through derivation analysis incorporating the PDI, R/S ratio, and QRS onset polarity in lead V1. The validation group analysis confirmed the proposed algorithm's high accuracy (95%), which was superior to the previous ones in predicting the AP side (p < 0.05). A score of ≤+1 was 96.5% accurate in predicting right AP while a score of ≥+2 was 92.5% accurate in predicting left AP. The new algorithm maintained optimal performance in specific subgroups of the global cohort showing an accuracy rate of 90%, 92%, and 96% in minimal pre-excitation, posteroseptal AP, and pediatric patients, respectively. CONCLUSIONS: A novel single-lead ECG algorithm incorporating the PDI interval with previous conventional criteria showed high accuracy in differentiating right from left manifest AP comprising pediatric and minimal pre-excitation subgroups in the current study.

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BACKGROUND: This study aimed to collect and analyze the literature data regarding Chiari network (CN) and other right atrium (RA) remnants comprising the Eustachian and Thebesian valves (EV, ThV) as a potential entrapment site during different percutaneous cardiac procedures (PCP). METHODS AND RESULTS: A systematic search was conducted using Pubmed and Embase databases following the PRISMA guidelines to obtain available data concerning PCP associated with entrapment of inserted materials within CN-EV-ThV. The final analysis included 41 patients who underwent PCP with reported material entrapment within these RA remnants. The PCP was atrial septal defect (ASD)/patent foramen ovale (PFO) closure, catheter ablation, and pacemaker/defibrillator implantation in 44%, 22%, and 17% of patients, respectively. The entrapped materials were ASD/PFO devices, multipolar electrophysiology catheters, passive-fixation pacing leads, and J-guidewires in about 30%, 20%, 15%, and 10% of patients, respectively. Intraprocedural transthoracic, transoesophageal and intracardiac echocardiography showed sensitivity to reveal these structures of 20%, ∼95%, and 100%, respectively. A percutaneous approach successfully managed 70% of patients, while cardiovascular surgery was required in 20% and three patients died (7.3%). CONCLUSIONS: CN and other RA remnants may cause entrapment of various devices or catheters during PCP requiring right heart access. The percutaneous approach, guided by intraprocedural imaging, appears safe and effective in managing most patients. Prevention includes recognizing these anatomical structures at baseline cardiac imaging and intraprocedural precautions. Further studies are needed to analyze the actual incidence of this condition, its clinical impact and appropriate management.

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INTRODUCTION: To evaluate the clinical outcomes of oral mexiletine (oMXT) to treat ventricular tachyarrhythmias (VTAs) in the era of implantable cardioverter-defibrillator (ICD) technology. EVIDENCE ACQUISITION: A systematic search was conducted using PubMed, Embase and Cochrane databases following the PRISMA guidelines to collect literature data reporting oMXT efficacy and safety outcomes in treating VTAs in ICD recipients. EVIDENCE SYNTHESIS: Final analysis included four studies accounting for a total of 91 patients with recurrent VTAs treated with oMXT. Amiodarone therapy was initially attempted in most patients (91.2%), while catheter ablation was performed in one-third of patients. VTA recurrences were observed in 55/91 patients (60.4%) during oMXT treatment compared to 91/91 (100%) before treatment (P<0.001). Appropriate therapies occurred in 55/88 ICD patients (62.5%) during oMXT treatment compared to 80/88 (90.9%) before treatment (P<0.001). After oMXT introduction, there was a significant reduction of the individual burden of VTA episodes and appropriate ICD therapies per patient, showing Hedges'g values of -1.103 (P=0.002) and -1.474 (P=0.008), respectively. Safety analysis showed a sample-weighted overall side-effect rate of 30%, while 21% of patients required drug reduction or discontinuation. Aggregated meta-regression analysis of the included studies and remote literature revealed a linear correlation between oMXT dosage and the overall side effects rate (r2 = 0.48; P=0.014). CONCLUSIONS: Oral mexiletine provides an adjunctive treatment to manage VTAs and reduces appropriate therapies in ICD patients with moderate efficacy and acceptable safety profiles. These observations await confirmation through randomised clinical trials.

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BACKGROUND: The risk of complications has been shown to be lower with subcutaneous implantable defibrillator (S-ICD) than with conventional ICDs. Given the low frequency of complications, experience of how to manage them is limited. In this paper, we describe generator- and lead-related complications recorded in a series of S-ICD patients, and we propose our conservative approach to managing them. METHODS: The study cohort consisted of S-ICD patients who were referred to our institution owing to generator- or lead-related complications requiring surgical intervention. With our "shift and cover" approach, the system component involved is moved from its original position to an alternative, more protected location. In the case of the generator, this involves moving it to an intermuscular pocket. In the case of infections at the parasternal scar, the electrode sleeve is moved away from its original location, stitched, and then covered with the muscular fascia. RESULTS: Fourteen S-ICD patients were referred to our institution owing to system-related complications. Complications involved the generator in 7 cases (deep pocket infections with erosion, extrusion, or pain), the lead in 5 cases (parasternal infections at the xyphoid incision site), and both the generator and the lead in 2 cases. Complications were managed without completely removing the device and resolved in a single surgical session with no intraoperative complications. During defibrillation testing, the first shock at 65 J was effective in all patients. The shock impedance after revision was significantly lower than that measured during first implantation (59 ± 10 Ohm versus 86 ± 24 Ohm, P = 0.013). In all cases, the cosmetic result was satisfactory. No complications or recurrent infections were reported at the 12-month follow-up visit. CONCLUSIONS: The proposed conservative approach was successful in managing S-ICD complications. The revision procedure allowed to optimize the system configuration in terms of the defibrillation vector, resulting in lower shock impedance values and better device positioning.

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AIMS: Air entrapment (AE) has been reported as a potential cause of early inappropriate shocks (ISs) following subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, but a cause-effect relationship is not always evident. This systematic review aims to analyse this phenomenon concerning implantation techniques, electrogram (EGM) features, radiologic findings, and patient management. METHODS AND RESULTS: A systematic search was conducted using PubMed, Embase, and Google Scholar databases following the PRISMA guidelines to obtain all available literature data since 2010 on S-ICD malfunctions possibly due to AE. The final analysis included 54 patients with AE as a potential cause of S-ICD malfunction. Overall, the aggregate incidence of this condition was 1.2%. Of ICD malfunctions possibly due to AE, 93% were ISs, and 95% were recorded within the first week following implantation. Radiologic diagnosis of AE was confirmed in 28% of the entire study cohort and in 68% of patients in whom this diagnostic examination was reported. At the time of device malfunction, EGMs showed artefacts, baseline drift, and QRS voltage reduction in 95, 76, and 67% of episodes, respectively. Management included ICD reprogramming or testing, no action (observation), and invasive implant revision in 57, 33, and 10% of patients, respectively. No recurrences occurred during follow-up, irrespective of management performed. CONCLUSIONS: Device malfunction possibly due to AE may occur in ∼1% of S-ICD recipients. Diagnosis is strongly suggested by early occurrence, characteristic EGM features, and radiologic findings. Non-invasive management, principally device reprogramming, appears to be effective in most patients.

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BACKGROUND: Antithrombotic/anticoagulation effects of direct oral anticoagulants (DOACs) are dose-dependent. However, recent observations suggest that administering lower dose DOACs may better protect against all-cause mortality. We investigated whether, in patients with established atherosclerosis, DOAC dose selection would affect the risk of all-cause mortality. METHODS: We performed a structured literature research for controlled trials allowing random assignment to a lower dose DOAC, a higher dose DOAC, or control therapy in patients with established atherosclerosis. Pooled risk ratios (RRs) of all-cause mortality in lower and higher dose DOACs versus control therapy were estimated using a random-effect model. RESULTS: Atherosclerosis manifested as acute coronary syndrome (n=17,220), stable coronary (CAD) and/or peripheral artery disease (PAD) (n=27,395) or CAD associated with atrial fibrillation (n=4,510). Antithrombotic doses of rivaroxaban (2.5 mg or 5.0 mg BID) or dabigatran (50 mg, 75 mg, 110 mg, or 150 mg, BID) were tested in three trials versus single or dual antiplatelet control therapy, whereas anticoagulation doses of edoxaban (30 mg or 60 OD) were tested versus warfarin in one trial. Compared to control, patients receiving lower dose (RR 0.80, 95% CI 0.73-0.89, p<0.0001, I²=0%), but not those receiving higher dose DOACs (RR 0.95, 95% CI 0.87-1.05, p=0.3074, I²=0%), had a significant reduction of all-cause mortality. Benefit from lower dose DOACs remained after sensitivity analysis or direct comparison with higher dose DOACs (RR 0.84, 95% CI 0.76-0.93, p=0.0009, I²=0%). CONCLUSIONS: Within antithrombotic/anticoagulation regimens of DOAC administration, selection of lower dose appears to protect from all-cause mortality in patients with established atherosclerosis.

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More than 2 decades ago, para-Hisian pacing was introduced to assess the pattern of retrograde conduction during electrophysiological studies. Although there is no ideal maneuver for every patient and condition, para-Hisian pacing is a valuable and handy strategy to differentiate between retrograde conduction over the atrioventricular node and the accessory pathways. The dynamic behavior of para-Hisian pacing, in a region with unique anatomical features, can produce various activation patterns and intriguing electrophysiological phenomena. Although the demonstration of a retrograde nodal activation pattern during para-Hisian pacing does not rule out the presence of an accessory pathway, evidence of retrograde conduction over an accessory pathway does not prove its active role in the culprit tachycardia. Multipolar His bundle recordings, detailed atrial mapping, and recognition of the truly captured structures and the impact of temporal changes of autonomic tone or pacing rates, are essential keys for accurate interpretation of this maneuver that may ultimately guide judicious catheter ablation of the arrhythmic substrate. This review aims to summarize the practical usefulness and potential pitfalls of the para-Hisian pacing maneuver, focusing on the interpretation of electrocardiograms and intracardiac recordings.

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This case concerns a 24-year-old female who developed malignant ventricular tachyarrhythmia a few weeks after pacemaker implantation for complete heart block. Apparently, right ventricular pacing caused significant repolarization abnormalities in both native and paced rhythms with marked QT prolongation and substantial electrical instability. This case highlights other intriguing phenomena in the puzzle of cardiac repolarization and how pacing therapy may alter this complex process providing arrhythmic substrate in vulnerable subjects. Though such arrhythmic events are clinically rare, vulnerable patients or with suspected myocardial disease that may cause QT prolongation should be carefully followed in the course of pacing therapy.

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The subcutaneous implantable cardioverter defibrillator (S-ICD) is a valuable alternative to the conventional trans-venous ICD (TV-ICD) for the prevention of sudden cardiac death (SCD). Prospective registries showed that the S-ICD is safe and effective in treating ventricular tachyarrhythmias in high-risk patients without pacing indications. While in earlier studies patients implanted with S-ICDs were young and mostly affected by channelopathies, contemporary S-ICD cohorts include patients with severely impaired left ventricular function and significant comorbidities. This review focuses on S-ICD evidence-based use and highlights current gaps between guidelines recommendations and real-world clinical practice.

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AIM: Ectopic atrial tachycardia (EAT) is a common arrhythmia in children, adolescents, and young adults. Radiofrequency (RF) ablation is often considered the treatment of choice in this population. We sought to evaluate the long-term follow-up after RF ablation. METHODS AND RESULTS: We retrospectively analyzed 36 young patients (age range 8-29 years), with clinical signs and symptoms suspected for EAT who underwent an electrophysiological study in our center. We evaluated the safety and acute success rate of ablation and the long-term follow-up. Ectopic foci were more frequently localized in the right atrium along the crista terminalis (28%) and EAT was successfully terminated in 97% of patients. At median follow-up (38 months), the recurrence rate was 20% with mostly recurrences expressed within 6 months. CONCLUSIONS: The study confirmed the safety and high acute success rate of EAT ablation in a population of children, adolescents, and young adults. Therefore, catheter ablation of EAT can be considered early in the course of treatment of these patients. The evidence of most recurrences within 6 months could be useful for advising patients on likely outcomes.

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