Etiology and device therapy in complete atrioventricular block in pediatric and young adult population: Contemporary review and new perspectives

Cardiac Conduction Disorders Due to Acquired or Genetic Causes in Young Adults: A Review of the Current Literature

Cardiac conduction disorders can manifest in young adults in isolated forms, associated with myocardial diseases or as part of a multiorgan disorder. Underlying causes of cardiac conduction disorders may be genetically determined or acquired. Cardiac conduction disorder in young adults is a complex and often underestimated and underrecognized disease that may need of a multidisciplinary team for the diagnosis, treatment, and long-term management of these patients. Therefore, it is crucial to raise clinicians' awareness of this condition. In this review, we provide a comprehensive update on the cause, diagnosis, and treatment of young adults with cardiac conduction disorders, also suggesting potential strategies to improve the current clinical management of these patients.

Rare Genetic Variants in Young Adults Requiring Pacemaker Implantation

BACKGROUND

Genetic disease has recently emerged as a cause of cardiac conduction disorders (CCDs), but the diagnostic yield of genetic testing and the contribution of the different genes to CCD is still unsettled.

OBJECTIVES

This study sought to determine the diagnostic yield of genetic testing in young adults with CCD of unknown etiology requiring pacemaker implantation. We also studied the prevalence of rare protein-altering variants across individual genes and functional gene groups.

METHODS

We performed whole exome sequencing in 150 patients with CCD of unknown etiology who had permanent pacemaker implanted at age ≤60 years at 14 Spanish hospitals. Prevalence of rare protein-altering variants in patients with CCD was compared with a reference population of 115,522 individuals from gnomAD database (control subjects).

RESULTS

Among 39 prioritized genes, patients with CCD had more rare protein-altering variants than control subjects (OR: 2.39; 95% CI: 1.75-3.33). Significant enrichment of rare variants in patients with CCD was observed in all functional gene groups except in the desmosomal genes group. Rare variants in the nuclear envelope genes group exhibited the strongest association with CCD (OR: 6.77; 95% CI: 3.71-13.87). Of note, rare variants in sarcomeric genes were also enriched (OR: 1.73; 95% CI: 1.05-3.10). An actionable genetic variant was detected in 21 patients (14%), with LMNA being the most frequently involved gene (4.6%).

CONCLUSIONS

Unrecognized rare genetic variants increase the risk of CCD in young adults with CCD of unknown etiology. Genetic testing should be performed in patients age ≤60 years with CCD of unknown etiology. The role of genetic variants in sarcomeric genes as a cause of CCD should be further investigated.

Severe cardiac conduction disease associated with titin gene mutation

Heart block is rare in pediatrics with many possible causes. An association between complete heart block (CHB) and pathogenic titin (TTN) mutations have not been previously described. We report a 9-year-old female with history of leukodystrophy and family history of atrial fibrillation who presented with syncope and conduction abnormalities, including CHB. She underwent pacemaker implantation and genetic testing demonstrated a pathogenic TTN mutation likely responsible for her cardiac findings. Our case suggests an association between TTN mutations and conduction disease and emphasizes broadening gene testing in assessing these patients, especially when a family history is present.

Recurrent cardiac arrest and complete atrioventricular block due to idiopathic coronary vasospasm: A case report

Recurrent complete atrioventricular block induced by coronary spasm is rare. We present a case of a 47-year-old woman who suffered from two episodes of out-of-hospital cardiac arrest within one year due to complete atrioventricular block caused by coronary vasospasm. No implantable cardioverter defibrillator was implanted after her first episode. As for the second episode, permanent brain injury was left behind despite successful cardiopulmonary resuscitation. She underwent a challenging rehabilitation process and an implantable cardioverter defibrillator was implanted before discharge. We captured the dynamic changes of the electrocardiogram during the episode with high temporal resolution. This case illustrates the importance of recognizing coronary spasm as a potential cause of complete atrioventricular block and highlights the need for implantable cardioverter defibrillator in such patients to improve survival and quality of life.

The risk of pediatric cardiovascular diseases in offspring born to mothers with systemic lupus erythematosus: a nationwide study

Background

Systemic lupus erythematosus (SLE), a common autoimmune disease predominantly affecting women, has been linked to various complications during pregnancy. The transfer of anti-Ro/SSA antibodies from SLE-affected mothers to their offspring can lead to neonatal lupus and cardiac issues. This study investigated the association between maternal SLE and the risk of pediatric cardiovascular disorders.

Methods

The study utilized South Korea's National Health Insurance Service (NHIS) database, covering 3,505,737 children born between 2007 and 2017 and tracked until 2020. Maternal SLE cases were identified using the World Health Organization's International Classification of Diseases Tenth revision (ICD-10) codes and linked with delivery records. Cardiologic disorders were categorized into congenital heart disease (CHD), arrhythmic disorders, and acquired heart disease. Propensity score matching with 1:4 ratios was applied to the set control group.

Results

Among 3,505,737 children, 0.7% (n = 23,330) were born to mothers with SLE. The incidence of preterm birth was significantly higher in the maternal SLE group (5.9% vs. 3.0%). Compared with the control group, children born to mothers with SLE exhibited a significantly elevated risk of overall CHDs (5.5%, adjusted odds ratio [aOR] 1.21; 95% confidence interval [CI] 1.14-1.29), including atrial septal defect (1.18; 1.09-1.28) and patent ductus arteriosus (1.15; 1.03-1.30). In addition, a notably higher risk was observed in arrhythmic disorders (complete atrioventricular block 7.20; 2.41-21.49) and acquired cardiac disorders, including cardiomyopathy (1.40; 1.17-1.68) and mucocutaneous lymph node syndrome (MCLS) (1.27; 1.15-1.43).

Conclusions

Maternal SLE is associated with congenital and acquired cardiac disorders in offspring, including structural, arrhythmic, and MCLS. This study highlights the need for continuous cardiovascular monitoring from the prenatal stage to preadolescence in these children due to multifactorial influences involving maternal autoantibodies, genetic predisposition, and environmental factors.

Peri-procedural and mid-term follow-up age-related differences in leadless pacemaker implantation: Insights from a multicenter European registry

BACKGROUND

Age-related differences on leadless pacemaker (LP) are poorly described. Aim of this study was to compare clinical indications, periprocedural and mid-term device-associated outcomes in a large real-world cohort of LP patients, stratified by age at implantation.

METHODS

Two cohorts of younger and older patients (≤50 and > 50 years old) were retrieved from the iLEAPER registry. The primary outcome was to compare the underlying indication why a LP was preferred over a transvenous PM across the two cohorts. Rates of peri-procedural and mid-term follow-up major complications as well as LP electrical performance were deemed secondary outcomes.

RESULTS

1154 patients were enrolled, with younger patients representing 6.2% of the entire cohort. Infective and vascular concerns were the most frequent characteristics that led to a LP implantation in the older cohort (45.8% vs 67.7%, p < 0.001; 4.2% vs 16.4%, p = 0.006), while patient preference was the leading cause to choose a LP in the younger (47.2% vs 5.6%, p < 0.001). Median overall procedural (52 [40-70] vs 50 [40-65] mins) and fluoroscopy time were similar in both groups. 4.3% of patients experienced periprocedural complications, without differences among groups. Threshold values were higher in the younger, both at discharge and at last follow-up (0.63 [0.5-0.9] vs 0.5 [0.38-0-7] V, p = 0.004).

CONCLUSION

When considering LP indications, patient preference was more common in younger, while infective and vascular concerns were more frequent in the older cohort. Rates of device-related complications did not differ significantly. Younger patients tended to have a slightly higher pacing threshold at mid-term follow-up.

Leadless Pacemaker Implantation in the Emergency Bradyarrhythmia Setting: Results from a Multicenter European Registry

Background. Data on leadless pacemaker (LPM) implantation in an emergency setting are currently lacking. Objective. We aimed to investigate the feasibility of LPM implantation for emergency bradyarrhythmia, in patients referred for urgent PM implantation, in a large, multicenter, real-world cohort of LPM recipients. Methods. Two cohorts of LPM patients, stratified according to the LPM implantation scenario (patients admitted from the emergency department (ED+) vs. elective patients (ED−)) were retrieved from the iLEAPER registry. The primary outcome of the study was a comparison of the peri-procedural complications between the groups. The rates of peri-procedural characteristics (overall procedural and fluoroscopic duration) were deemed secondary outcomes. Results. A total of 1154 patients were enrolled in this project, with patients implanted due to an urgent bradyarrhythmia (ED+) representing 6.2% of the entire cohort. Slow atrial fibrillation and complete + advanced atrioventricular blocks were more frequent in the ED+ cohort (76.3% for ED+ vs. 49.7% for ED−, p = 0.025; 37.5% vs. 27.3%, p = 0.027, respectively). The overall procedural times were longer in the ED+ cohort (60 (45−80) mins vs. 50 (40−65) mins, p < 0.001), showing higher rates of temporary pacing (94.4% for ED+ vs. 28.9% for ED−, p < 0.001). Emergency LPM implantation was not correlated with an increase in the rate of major complications compared to the control group (6.9% ED+ vs. 4.2% ED−, p = 0.244). Conclusion. LPM implantation is a feasible procedure for the treatment of severe bradyarrhythmia in an urgent setting. Urgent LPM implantation was not correlated with an increase in the rate of major complications compared to the control group, but it was associated with longer procedural times.

Atrial Flutter in Particular Patient Populations

"Despite being one of the best understood cardiac arrhythmias, the clinical meaning of atrial flutter varies according to the specific context, and its optimal treatment may be limited by both the suboptimal response to rate/rhythm control drugs and by the complexity of the underlying substrate. In this article, we present a state-of-the-art overview of mechanisms, prognostic impact, and medical/interventional management options for atrial flutter in several specific patient populations, including heart failure, cardiomyopathies, muscular dystrophies, posttransplant patients, patients with respiratory disorders, athletes, and subjects with preexcitation, aiming to stimulate further research in this challenging field and facilitate appropriate patient care."