Oral mexiletine for ventricular tachyarrhythmias treatment in implantable cardioverter-defibrillator patients: a systematic review of the literature

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.

Practical Considerations for Cardiac Electronic Devices Reimplantation Following Transvenous Lead Extraction Due to Related Endocarditis

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.

Catheter-induced right bundle branch block: Practical implications for the cardiac electrophysiologist

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.

Catheter ablation of left atrial tachycardia adjacent to a septal closure device: A multifaceted challenge?

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.

Chiari network for the interventional cardiologist: A hidden enemy at the heart gate - A systematic review of the literature

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.

A Single-lead ECG algorithm to differentiate right from left manifest accessory pathways: A reappraisal of the P-Delta interval

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.

952 SAFETY OF CLASS IC ANTIARRHYTHMIC DRUGS IN CORONARY ARTERY DISEASE PATIENTS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Introduction

Class IC antiarrhythmic drugs (AADs) currently represent a cornerstone in the therapy of atrial fibrillation (AF). They also play an important role in the treatment of idiopathic ventricular arrhythmias. Following the results of the CAST study flecainide and by extension the other class IC AADs were contraindicated in patients with ischemic and structural heart disease, because of their proarrhythmic effect and the consequent increase in mortality observed in the study.

Recent studies, carried out on patients with chronic coronary heart disease, have shown a good safety profile for this class of drugs.

Methods

The aim of our study was to evaluate the mortality and the mortality rate in patients affected by ischaemic heart disease who take Class IC AADs. A systematic review and meta-analysis was conducted using Pubmed and Embase databases, following the PRISMA guidelines, to collect literature data reporting Class IC AADs safety in patients affected by coronary artery disease.

Results

The final analysis included four studies accounting for a total of 3643. In the Classe IC AADs group the events (all cause death) were observed in 104/1170 patients, while in the control group were observed in 338/2473 patients, showing an ODDS ratio of 1.431 (IC 0.748-2.740), p value 0.279 (TABLE 1A). The event rate per year was 5,5% in the CLASS IC AADs group and 5,1 in the control group, with an ODDS ratio of 1.524 (IC 0.807-2.879), p value 0.194 (TABLE 1B).

Conclusion

Class IC AADs doesn't increase the overall mortality and mortality rate in patient affected by icheamic heart disease. These observations await confirmation through randomised clinical trial.

Air entrapment as a potential cause of early subcutaneous implantable cardioverter defibrillator malfunction: a systematic review of the literature

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.

Secondary hemophagocytic lymphohystiocytosis in a Rubinstein Taybi syndrome patient

Rubinstein-Taybi syndrome (RSTS) is an autosomal dominant disorder, caused by variants in CREBBP or EP300. Affected individuals present with distinctive craniofacial features, broad thumbs and/or halluces, intellectual disability and immunodeficiency. Here we report on one RSTS patient who experienced hemophagocytic lymphohystiocytosis (HLH) and disseminated herpes virus 1 ( HSV-1) disease. The clinical picture of RSTS is expanding to include autoinflammatory, autoimmune, and infectious complications. Prompt treatment of HLH and disseminated HSV-1 can lower the mortality rate of these life-threatening conditions.

Para-Hisian Pacing: New Insights of an Old Pacing Maneuver

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.

Nearly fatal ventricular arrhythmia following pacemaker implantation in a young female with complete heart block

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.

The subcutaneous implantable cardioverter-defibrillator: Current trends in clinical practice between guidelines and technology progress

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.

Long-term follow-up after radiofrequency ablation of ectopic atrial tachycardia in young patients

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.

Supraventricular arrhythmia with discordant electrocardiographic features: What is the arrhythmia mechanism?

Junctional and AV nodal reentrant tachycardia share common electrocardiographic features, but they differ in their management and outcomes after catheter ablation. This case concerns a 60-year-old female who presented with recurrent episodes of a relatively slow, regular supraventricular arrhythmia. Electrocardiographic features of the arrhythmia were discordant regarding its underlying mechanism. However, careful analysis of 12-lead electrocardiograms, with focus on the effect of spontaneous premature beats, pointed out the arrhythmia etiology. Electrophysiological study and pacing maneuvers defined the arrhythmic substrate that was successfully treated by catheter ablation.

Entirely subcutaneous defibrillator and complex congenital heart disease: Data on long-term clinical follow-up

AIM

To describe the long-term follow-up of patients with complex congenital heart disease who underwent subcutaneous implantable cardiac defibrillator (S-ICD), focusing on local complications, appropriate and inappropriate shocks.

METHODS

Patients with complex congenital heart disease underwent S-ICD implant in two centers with the conventional technique. Data at follow-up were retrieved from clinical notes and institutional database.

RESULTS

Eight patients were implanted in two centres between 2010 and 2016. Median age at implant was 37.5 years (range 13-57). All patients who were deemed suitable for S-ICD implant passed the pre-procedural screening. Three patients were previously implanted with a anti-bradycardia device, one of whom with CRT. In one patient the device was explanted due to local infection. During the total median follow-up of 874 d, one patient had an appropriate and one inappropriate shock triggered by fast atrial tachycardia. None of the patients had inappropriate shocks secondary to T wave oversensing or electrical interference with anti- bradycardia devices.

CONCLUSION

S-ICD appears to be effective and safe in patients with complex congenital heart disease.

A narrow QRS tachycardia and cannon A waves: What is the mechanism?

Regular narrow QRS tachycardia, particularly if well-tolerated, is usually considered a "benign" arrhythmia of a supraventricular origin. This case concerns an 82-year-old male with ischemic heart disease who presented with recurrent episodes of a narrow QRS tachycardia that was initially diagnosed and treated as atrial tachyarrhythmia. However, careful physical examination and ECG analysis established the correct diagnosis, and the patient was managed appropriately. Remarkably, the observation of irregular cannon A waves, and Lewis lead recording, confirmed atrioventricular dissociation during tachycardia and indicated its underlying mechanism.

Commotio Cordis and complete heart block: Where is the block level?

Ventricular fibrillation is typically the initial arrhythmia in commotio cordis following precordium impacts that occur within an electrically vulnerable period of the cardiac cycle. Conversely, complete heart block is very rare in this context, and its mechanism and temporal course are poorly understood. The presented case concerns a 12-year-old boy, athletic skier, who developed a transient complete heart block following commotio cordis. The electrocardiographic features, the proposed block level and mechanisms of complete heart block following commotio cordis are discussed.

Is It Complete Left Bundle Branch Block? Just Ablate the Right Bundle

Complete left bundle branch block (LBBB) is established according to standard electrocardiographic criteria. However, functional LBBB may be rate-dependent or can perpetuate during tachycardia due to repetitive concealed retrograde penetration of impulses through the contralateral bundle "linking phenomenon." In this brief article, we present two patients with basal complete LBBB in whom ablating the right bundle unmasked the actual antegrade conduction capabilities of the left bundle. These cases highlight intriguing overlap between electrophysiological concepts of complete block, linking, extremely slow, and concealed conduction.

Adenosine and Preexcitation Variants: Reappraisal of Electrocardiographic Changes

Intravenous adenosine is a short-acting blocker of the atrioventricular node that has been used to unmask subtle or latent preexcitation, and also to enable catheter ablation in selected patients with absent or intermittent preexcitation. Depending on the accessory pathway characteristics, intravenous adenosine may produce specific electrocardiographic changes highly suggestive of the preexcitation variant. Herein, we view different ECG responses to this pharmacological test in various preexcitation patterns that were confirmed by electrophysiological studies. Careful analysis of electrocardiographic changes during adenosine test, with emphasis on P-delta interval, preexcitation degree, and atrioventricular block, can be helpful to diagnose the preexcitation variant/pattern.

Treatment of inappropriate sinus tachycardia with ivabradine

BACKGROUND

Inappropriate sinus tachycardia (IST) often causes palpitations, dyspnea, and exercise intolerance, that are generally treated with beta blockers and non-dihydropyridine calcium-channel antagonists. Ivabradine, a selective inhibitor of cardiac pacemaker If current, has recently emerged as an effective and safe alternative to conventional drugs for IST.

METHODS

We performed a systematic overview of clinical studies on the therapeutic yield of ivabradine in patients with inappropriate sinus tachycardia, published in MEDLINE database from January 2000 to March 2015.

RESULTS

Overall, five case reports were found, all showing efficacy of ivabradine in subjects affected by IST. Eight non-randomized clinical studies demonstrated short- and medium-term safety and efficacy of ivabradine administration in IST, also in adjunction to or in comparison with metoprolol. One double-blind randomized crossover study also showed that ivabradine is superior to placebo for heart rate (HR) reduction and symptoms control in patients affected by IST.

CONCLUSIONS

Ivabradine is effective and safe in short- and medium-term treatment of IST. However, long-term follow-up studies and randomized studies comparing ivabradine with beta blockers are still lacking.

Follow up in a developing country of patients with complete atrio-ventricular block

Aim

The purpose of the study was to assess the incidence and survival rate of patients with complete atrio-ventricular block in the cardiac centre of St Elizabeth Catholic General Hospital, Kumbo, Cameroon.

Methods

Between 2009 and 2011, 26 patients with complete atrio-ventricular block were diagnosed at our institution. Complete atrio-ventricular block was defined as complete heart block, diagnosed by echocardiographic or electrocardiographic documentation of the dissociation between electrical activity of the atria and ventricles. Hospital charts, electrocardiograms (ECG), echocardiography and chest radiography were reviewed.

Results

The triad of symptoms that pointed to the diagnosis of complete atrio-ventricular block was mainly fatigue, shortness of breath on mild physical exertion, and dizziness. The median age at diagnosis was 65 ± 15 years. The escape rhythm showed a narrow QRS complex in 35.2% of patients, whereas wide QRS complexes were seen in 64.8%. In only 15 patients were pacemakers implanted: dual-chamber in 10 and single-chamber in five cases, depending on the availability of the pacemakers. During the observational period, five non-implanted patients died, giving a mortality rate of 45%. We recorded no deaths in patients with pacemakers.

Conclusion

In developing countries, natural selection is observed in patients with complete atrio-ventricular block. Lack of infrastructure and early detection, and financial limitations are the main problems faced in the follow up of these patients. Re-organisation of the public health system, new programmes for the prevention of cardiovascular diseases, and government subsidisation are needed in our milieu.

Anonymization of Statistical Data

In the modern digital society, personal information about individuals can be collected, stored, shared and disseminated much more easily and freely. Such data can be released in “macrodata” form, reporting aggregated information, or in “microdata” form, reporting specific information on individual respondents. To ensure proper privacy of individuals as well of public and private organizations, it is then important to protect possible sensitive information in the original dataset from either direct or indirect disclosure. In this paper, we characterize macrodata and microdata releases and then focus on microdata protection. We provide a characterization of the main microdata protection techniques and describe recent solutions for protecting microdata against identity and attribute disclosure, discussing some open issues that need to be investigated.

[Adult with congenital heart disease: an overview]

The improvement of surgical procedures over the past 40 years has changed the medical history of the congenital heart defect. It is estimated that 85% of children with congenital heart disease now have the opportunity to reach adulthood and that this percentage will increase over the next two decades. This special issue of the Journal aims to offer a basic information on key topics of this field of cardiology not newer, but still rapidly evolving.