T-Wave Oversensing in Patients With Brugada Syndrome: True Bipolar Versus Integrated Bipolar Implantable Cardioverter Defibrillator Leads

Left ventricular T-wave sensing by a CRT-D device

This report describes the occurrence of T wave sensing by the left ventricular (LV) channel of implantable defibrillators with cardiac resynchronization therapy (CRT-D devices) of Biotronik during biventricular pacing. This finding is different from reported cases that involved T-wave wave sensing by the right ventricular channel of CRT devices.

Self-supervised VICReg pre-training for Brugada ECG detection

Existing deep learning algorithms for electrocardiogram (ECG) classification rely on supervised training approaches requiring large volumes of reliably labeled data. This limits their applicability to rare cardiac diseases like Brugada syndrome (BrS), often lacking accurately labeled ECG examples. To address labeled data constraints and the resulting limitations of supervised training approaches, we developed a novel deep learning model for BrS ECG classification using the Variance-Invariance-Covariance Regularization (VICReg) architecture for self-supervised pre-training. The VICReg model outperformed a state-of-the-art neural network in all calculated metrics, achieving an area under the receiver operating and precision-recall curves of 0.88 and 0.82, respectively. We used the VICReg model to identify missed BrS cases and hence refine the previously underestimated institutional BrS prevalence and patient outcomes. Our results provide a novel approach to rare cardiac disease identification and challenge existing BrS prevalence estimates offering a framework for other rare cardiac conditions.

Lights and shadows of subcutaneous implantable cardioverter-defibrillator in Brugada syndrome

Currently the cornerstone of therapy for ventricular arrhythmic complications and sudden cardiac death prevention in Brugada syndrome (BrS) is an implantable cardioverter-defibrillator (ICD). BrS patient population differs from the majority of patients with an ICD implanted for structural heart disease, and as widely known, transvenous ICD (TV-ICD) systems have been associated with high complication rates in patients with BrS. Technological evolution of these devices has certainly reduced complications due to the device itself, but a careful preimplant screening of these patients is still essential. To date, criteria for an adequate screening process to select suitable candidates for a subcutaneous implantable cardioverter-defibrillator (S-ICD) from patients with BrS are sometimes nonstandardized and often lack important precautions that are instead fundamental to select the most suitable type of ICD for these patients. To better select suitable candidates for an S-ICD from patients with BrS, a full screening process should include screening during or immediately after an exercise test and after a drug provocation challenge test. We report an analysis of the "lights and shadows" of S-ICD for a correct use of this device in patients with BrS.

Electromagnetic interference from left ventricular assist devices detected in patients with implantable cardioverter-defibrillators

INTRODUCTION

Electromagnetic interference (EMI) from left ventricular assist devices (LVADs) can cause implantable cardioverter-defibrillator (ICD) oversensing. We sought to assess the frequency of inappropriate shocks/oversensing due to LVAD-related EMI and prospectively compare integrated (IB) versus dedicated bipolar (DB) sensing in patients with LVADs.

METHODS

Single-center study in LVAD patients with Medtronic or Abbott ICDs between September 2017 and March 2020. We excluded patients that were pacemaker dependent. Measurements were obtained of IB and DB sensing and noise to calculate a signal-to-noise ratio (SNR). Device checks were reviewed to assess appropriate and inappropriate sensing events.

RESULTS

Forty patients (age 52 ± 14 years, 75% men, 38% ischemic cardiomyopathy) were included with the median time between LVAD implantation and enrollment of 6.7 months (2.3, 11.4 months). LVAD subtypes included: HeartWare (n = 22, 55%), Heartmate II (n = 10, 25%), and Heartmate III (n = 8, 20%). Over a follow-up duration of 21.6 ± 12.9 months after LVAD implantation, 5% of patients (n = 2) had oversensing of EMI from the LVAD (both with HeartWare LVADs and Abbott ICDs) at 4 days and 10.8 months after LVAD implantation. Both patients underwent adjustment of ventricular sensing with resolution of oversensing and no further events over 5 and 15 months of further follow-up. The SNR was similar between IB and DB sensing (50 [29-67] and 57 [41-69], p = 0.89).

CONCLUSION

ICD oversensing of EMI from LVADs is infrequent and can be managed with reprogramming the sensitivity. There was no significant difference in the R-wave SNR with IB versus DB ICD leads.

Update on Brugada Syndrome 2019

Brugada syndrome (BrS) was first described in 1992 as an aberrant pattern of ST segment elevation in right precordial leads with a high incidence of sudden cardiac death (SCD) in patients with structurally normal heart. It represents 4% ∼ 12% of all SCD and 20% of SCD in patients with structurally normal heart. The extremely wide genetic heterogeneity of BrS and other inherited cardiac disorders makes this new area of genetic arrhytmology a fascinating one. This review shows the state of art in diagnosis, management, and treatment of BrS focusing all the aspects regarding genetics and Preimplant Genetic Diagnosis (PGD) of embryos, overlapping syndromes, risk stratification, familial screening, and future perspectives. Moreover the review analyzes key points like electrocardiogram (ECG) criteria, the role of electrophysiological study (the role of ventricular programmed stimulation and the need of universal accepted protocol) and the importance of a correct risk stratification to clarify when implantable cardioverter defibrillator or a close follow-up is needed. In recent years, cardiovascular studies have been focused on personalized risk assessment and to determine the most optimal therapy for an individual. The BrS syndrome has also benefited of these advances although there remain several key points to be elucidated. We will review the present knowledge, progress made, and future research directions on BrS.

Meta-Analysis of Clinical Outcome After Implantable Cardioverter-Defibrillator Implantation in Patients With Brugada Syndrome

OBJECTIVES

This study sought to summarize the clinical outcome of implantable cardioverter-defibrillator (ICD) therapy in patients with Brugada syndrome.

BACKGROUND

Brugada syndrome is characterized by cardiac conduction abnormalities and a high risk of ventricular arrhythmias that may result in sudden cardiac death. A complete overview of clinical outcome, appropriate and inappropriate interventions, and complications after ICD therapy in patients with Brugada syndrome is lacking.

METHODS

The online MEDLINE database was searched for published reports and yielded 828 studies on outcome and complications after ICD therapy in patients with Brugada syndrome. After careful evaluation, 22 studies including a total of 1,539 patients were included in the meta-analysis.

RESULTS

In total, 1,539 patients (mean age 45 years, 18% women) underwent ICD implantation for primary (79%) or secondary (21%) prevention of sudden cardiac death. During a mean follow-up of 4.9 years, the appropriate and inappropriate ICD intervention rates were 3.1 and 3.3 per 100 person-years, respectively. The cardiac mortality rate was 0.03 per 100 person-years and noncardiac mortality rate was 0.3 per 100 person-years. ICD-related complications per 100 person-years consisted of lead malfunction (1.6), psychological complication (1.3), infection (0.6), lead dislocation (0.4), and any complication (0.6).

CONCLUSIONS

Patients with Brugada syndrome judged to be at high risk for ventricular arrhythmia may significantly benefit from ICD therapy, which is associated with an appropriate ICD intervention rate of 3.1 per 100 person-years and low cardiac and noncardiac mortality rates. Inappropriate ICD interventions and ICD-related complications may lead to considerable morbidity.

T-wave oversensing is more dependent on ICD sensitivity algorithm than lead sensing configuration

Modern implantable cardioverter defibrillators (ICD) employ dynamic sensing algorithms in order to protect against fine ventricular fibrillation without oversensing intrinsic activity. We present a patient with a Medtronic ICD who had inhibition of pacing and not inappropriate shocks due to T wave oversensing (TWOS) in both true bipolar (TB) and integrated bipolar (IB) sensing configurations. Rather than alternatives such as lead revision or programming to an unacceptably insensitive value, this was solved by exchanging for a Boston Scientific ICD. Although the literature suggests lead sensing configuration impacts TWOS, this case demonstrates ICD sensitivity algorithm may be a key determinant.

Prognosis, risk stratification, and management of asymptomatic individuals with Brugada syndrome: A systematic review

Brugada syndrome (BrS) is a primary electrical disease associated with increased risk of sudden cardiac death due to polymorphic ventricular arrhythmias. The prognosis, risk stratification, and management of asymptomatic individuals remain the most controversial issues in BrS. Furthermore, the decision to manage asymptomatic patients with an implantable cardioverter-defibrillator should be made after weighing the potential individual risk of future arrhythmic events against the risk of complications associated with the implant and follow-up of patients living with such devices, and the accompanying impairment of the quality of life. Several clinical, electrocardiographic, and electrophysiological markers have been proposed for risk stratification of subjects with BrS phenotype, but the majority have not yet been tested in a prospective manner in asymptomatic individuals. Recent data suggest that current risk factors are insufficient and cannot accurately predict sudden cardiac death events in this setting. This systematic review aims to discuss contemporary data regarding prognosis, risk stratification, and management of asymptomatic individuals with diagnosis of Brugada electrocardiogram pattern and to delineate the therapeutic approach in such cases.

Patients With Brugada Syndrome and Implanted Cardioverter-Defibrillators: Long-Term Follow-Up

BACKGROUND

Implantable cardioverter-defibrillator (ICD) indications for primary prevention in Brugada syndrome (BrS) are still debated.

OBJECTIVES

The authors investigated the long-term outcome after ICD implantation in a large cohort of BrS patients.

METHODS

Of a total of 370 patients with BrS in follow-up (age 43 ± 14 years; 74% male), 104 patients (28.1%) were treated with ICDs. The authors analyzed the long-term incidence of shocks and complications.

RESULTS

An ICD was implanted for secondary prevention in 10 patients (9.6%) and for primary prevention in 94 patients (90.4%). After a follow-up of 9.3 ± 5.1 years, 21 patients (20.2%) experienced a total of 81 appropriate shocks (incidence rate 2.2 per 100 person-years). The rate of appropriate shocks was higher in secondary prevention patients (p < 0.01). However, 4 of the 45 asymptomatic patients (8.9%) experienced appropriate ICD therapy, all with a spontaneous type 1 electrocardiogram and inducible ventricular arrhythmias. In the multivariable analysis, type 1 electrocardiogram with syncope (hazard ratio: 4.96; 95% confidence interval: 1.87 to 13.14; p < 0.01) and secondary prevention indication (hazard ratio: 6.85; 95% confidence interval: 2.29 to 20.50; p < 0.01) were significant predictors of appropriate therapy. Nine patients (8.7%) experienced 37 inappropriate shocks (incidence rate 0.9 per 100 person-years). Twenty-one patients (20.2%) had other ICD-related complications (incidence rate 1.4 per 100 person-years). Three patients (2.9%) died (1 electrical storm and 2 noncardiovascular deaths).

CONCLUSIONS

ICD therapy is an effective therapy in high-risk patients with BrS. However, it is also associated with a significant risk of device-related complications. Special care during ICD implantation, adequate device programming, and regular follow-up may allow reducing the number of adverse events.

Inappropriate shocks from a subcutaneous implantable cardioverter-defibrillator due to oversensing during periods of rate-related bundle branch block

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a novel technology with proven efficacy in sudden cardiac death prevention; however, there is a lack of long-term safety data. We describe the case of a 55-year-old female patient implanted with an S-ICD due to idiopathic ventricular fibrillation, who subsequently presented with inappropriate shocks leading to ventricular fibrillation that was successfully terminated by another shock. Inappropriate shocks were due to intermittent T wave oversensing during periods of rate-dependent right bundle branch block. Assessment of the S-ICD electrograms during an exercise test allowed successful reprogramming of the device׳s sensing vector with no further events.

Two to one CRTD pacing: When the T wave and the P wave interact

We presented a unique phenomenon of 2:1 cardiac resynchronization therapy pacing due to T wave oversensing. Ultimately, by utilizing a unique feature of integrated bipolar sensing, we succeeded to eliminate the T wave oversensing signals, and restore 1:1 CRTD pacing. Importantly, this feature enabled us to overcome the T wave oversensing issue, without the need to decrease the ventricular sensitivity, which could potentially interfere with ventricular arrhythmia detection and appropriate shock delivery when required.

Device rounds: T-wave oversensing: A cause of loss of cardiac resynchronization therapy

A CRT-D patient presented with loss of biventricular pacing associated with heart failure symptoms. The electrocardiogram showed sinus rhythm with alternating wide unpaced and narrower paced QRS complexes. Device interrogation showed T-wave oversensing on all paced biventricular beats, with the following sinus P-wave not tracked due to it falling in the post-ventricular atrial refractory period, leading to intrinsic conduction. Device reprogramming from true bipolar (RV tip to RV ring) sensing to integrated bipolar (RV tip to RV coil) resolved the problem without having to decrease sensitivity values, allowing biventricular pacing close to 100% to resume with improvement of symptoms. T-wave oversensing is a frequently recognised cause of inappropriate therapy in implantable cardioverter defibrillators, but less frequently as a cause of loss of biventricular pacing in CRT-Ds. We review the different non-invasive strategies to overcome this problem.