Ventricular Arrhythmia in the Fontan Circulation:Prevalence,Risk Factors and Clinical Implications

Objective:Sudden cardiac death(SCD)and malignant ventricular arrhythmia(VA)are increasingly recognized as important issues for people living with a Fontan circulation,but data are lacking.We sought to characterize the cohort who had sudden cardiac death,most likely related to VA and/or documented VA in the Australia and New Zealand Fontan Registry including risk factors and clinical outcomes.Methods:A retrospective cohort study was performed.Inclusion criteria were documented non-sustained ventricular tachycardia,sustained ventricular tachycardia,ventricular fibrillation,resuscitated cardiac arrest or SCD>30 days post-Fontan completion.Results:Of 1611 patients,20(1.2%)had VA;14(1.0%)had VA without SCD and 6(<1%)had SCD(6%of all deaths recorded in Registry;5 of those had documented VA at the time of arrest and 1 was presumed to be VA-associated).The median age at first VA was 20.5(14–32)years,10(50%)were females,and the median age at Fontan operation was 8(4–17)years.On univariable analysis,hypoplastic left heart syndrome(p=0.03)and older age Fontan operation(p<0.001)were associated with VA.Earlier Fontan era(p<0.003),atriopulmonary Fontan(p<0.001),pre-Fontan atrioventricular valve repair(p=0.013)pre-or post-Fontan atrial arrhythmia(p=0.010)were associated with SCD.Patients with VA had a 3 times higher risk of death or heart transplant(HR 3.27(1.19,8.98),p=0.02).Conclusions:A proportion of people living with a Fontan circulation have malignant VA.Routine VA screening in this cohort is essential.More data are needed to aid risk stratification.

Importance of clinical suspicion and multidisciplinary management for early diagnosis of a cardiac laminopathy patient:A case report

BACKGROUND Laminopathies are rare diseases,whose cardiac manifestations are heterogeneous and,especially in their initial stage,similar to those of more common conditions,such as ischemic heart disease.Early diagnosis is essential,as these conditions can first manifest themselves with sudden cardiac death.Electrical complications usually appear before structural complications;therefore,it is important to take into consideration these rare genetic disorders for the differential diagnosis of brady and tachyarrhythmias,even when left ventricle systolic function is still preserved.CASE SUMMARY A 60-year-old man,without history of previous disorders,presented in September 2019 to the emergency department because of the onset of syncope associated with hypotension.The patient was diagnosed with a high-grade atrioventricular block.A dual chamber pacemaker was implanted,but after the onset of a sustained ventricular tachycardia during physical exertion,a drug eluting stent was implanted on an intermediate stenosis on the left anterior descending artery,which had previously been considered non-haemodynamically significant.During the follow-up,the treating cardiologist,suspicious of the overall clinical picture,recommended a genetic test for the diagnosis of cardiomyopathies,which tested positive for a pathogenetic mutation of the lamin A/C gene.While awaiting the result of the genetic test and,later,the pacemaker to be upgraded to a biventricular defibrillator,a remote monitoring device was given to the patient in 2019-related lockdown.CONCLUSIONThis case aims to raise awareness of the cardiological manifestations of laminopathies,which can be dangerously misdiagnosed as other, more common conditions.

Arrhythmogenic properties of dismantling cadherin-mediated adhesion in murine hearts

Objective： To evaluate the arrhythmogenic effects of dismantling cadherin-mediated adhesion by recombinant mouse aminopeptidase N （rmAPN） in murine hearts. Methods： rmAPN was incubated with cultured neonatal rat cardiomyocytes as well as being infused in adult mice. The cell-cell connections were immunolabelled and observed by laser confocal microscopy. Disruption of the N-terminal of N-cadherin （N-cad） was detected by western blot and quantitative immunofluorescence. The risk of inducible ventricular tachyarrhythmia was evaluated in mice by an electrophysiological study. Results： Disrupted cell-cell contact was observed in cultured neonatal rat cardiomyocytes in response to 30-40 ng/μL rmAPN. Loss of the N-terminal in N-cad and altered distribution of connexin 43 （Cx43） were observed in hearts from rmAPN-infused mice. In addition, a reduction of phosphorylated Cx43 was also detected concomitant with redistribution of Cx43. Electrophysiological studies of rmAPN-infused mice showed prolonged QRS duration and increased inducibility of ventricular tachycardias. Conclusion： Disruption of N-cad by rmAPN contributes to gap junction remodeling and may elicit arrhythmogenic effects. The disorder of adherent junctions by proteolytic enzymes may play an important role in arrhythmogenic mechanisms in correlated diseases.

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia

Background Implantable cardioverter defibrillator （ICD） is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital. Methods From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis. Results No arrhythmic event was detected in 12/50 （24%） patients during the period of follow-up. Among the remaining patients, 11 （22%） experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia （VT） and 108 ventricular fibrillation （VF） episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings （ATPs） and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 （14.3%） inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 （26.9%） inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation （AF） with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation. Conclusions About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.

Home monitoring system improves the detection of ventricular arrhythmia and inappropriate shock

Background The impact of home monitoring system in the early detection of ventricular arrhythmia and inappropriate shock in daily work is not clear. The aim of this study was to investigate the impact of home monitoring system on the early detection of ventricular arrhythmia and inappropriate shock in daily clinical practice. Methods Cases of implantable cardioverter defibrillator （ICD） implantation with or without the home monitoring system from June 2010 to October 2011 at our center were reviewed. Follow-up was scheduled after implantation. Data relating to the home monitoring ICD were retrieved using a remote transmitter system. Data relating to the other devices were obtained during scheduled follow-up or unscheduled visits. Results Our study involved 69 patients （mean age （68.4＋17.6） years, 64.3% males, 26 in the home monitoring group vs. 43 in the non-home monitoring group）. In all, 561 ventricular arrhythmia episodes were detected in 17 patients （39.5%） in the non-home monitoring group： 495 episodes were ventricular tachycardia and 66 episodes were ventricular fibrillation; among these, 476 episodes of ventricular tachycardia and 45 episodes of ventricular fibrillation were appropriately diagnosed （96.1% and 68.2%, respectively）. In the home monitoring group, 389 ventricular arrhythmia episodes were transmitted by the home monitoring system in nine patients （34.6%）： 348 ventricular tachycardia episodes and 41 ventricular fibrillation episodes. Device detection was appropriate in 348 ventricular tachycardia episodes （100.0%） and 36 ventricular fibrillation episodes （87.8%）. The home monitoring group showed a higher appropriate detection rate of ventricular tachycardia （P 〈0.01） and ventricular fibrillation （P=0.02）. The proportion of inappropriate shock was comparable in the two groups （6/11 in the non-home monitoring group vs. 1/7 in the home monitoring group; m=0.08）. Conclusions The home monitoring ICD was able to provide information relating to inappropriate detection and shock earlier than conventional devices. It proved to be a reliable tool and has a strong potential to provide greater reaction time in the case of inappropriate shock.