The entirely subcutaneous ICDTM system in patients with congenital heart disease: experience from a large single-centre analysis

Risk Stratification for Sudden Cardiac Death in Repaired Tetralogy of Fallot

There has been significant progress in the prevention of sudden cardiac death in repaired tetralogy of Fallot. Contemporary cohorts report greater survival attributable to improved surgical techniques, heart failure management, and proactive strategies for risk stratification and management of ventricular arrhythmias including defibrillator implantation and ablation technology. Over the last 25 years, our understanding of predictive risk factors has also improved from invasive and more limited measures to individualized risk prediction scores based on extensive demographic, imaging, electrophysiological, and functional data. Although each of these contemporary scoring systems improves prediction, there are important differences between the study cohorts, included risk factors, and imaging modalities that can significantly affect interpretation and implementation for the individual patient. In addition, accurate phenotyping of disease complexity and anatomic repair substantially modulates this risk and the mechanism of sudden death. Routine implementation of risk stratification within repaired tetralogy of Fallot management is important and directly informs primary prevention defibrillator implantation as well as consideration for proactive invasive strategies including ventricular tachycardia ablation and pulmonary valve replacement. Assessment and risk stratification by a multidisciplinary team of experts in adult congenital heart disease are crucial and critical. Although we have increased understanding, reconciliation of these complex factors for the individual patient remains challenging and often requires careful consideration and discussion with multidisciplinary teams, patients, and their families.

Combined subcutaneous implantable cardioverter defibrillator and pacemaker devices in complex congenital heart disease: a single-center experienced based study

BACKGROUND

Subcutaneous implantable cardioverter defibrillators (S-ICD) are widely accepted therapy in congenital heart disease (CHD) patients at risk of life-threatening ventricular arrhythmias or sudden cardiac death (SCD) when pacing is not required. Occasionally, pacemaker (PM)-dependent CHD patients will subsequently develop an indication for a cardioverter defibrillator. The use of S-ICD in complex CHD patients who have had already PM devices implanted implies some specific considerations, as the safety for these patients in unknown and recommendations among physicians may vary widely.

METHODS

We review the data and studied the indications for S-ICD in complex CHD with previous PM and discuss its usefulness in clinical practice.

RESULTS

From a large cohort of 345 patients enrolled in the S-ICD Monaldi care registry, which encompass all the patients implanted in the Monaldi Hospital of Naples, we considered 11 consecutive complex CHD patients (10M/1F aged 40.4 ±18.4 years) who underwent S-ICD implant after a previous PM implant, from February 2015 to October 2022. Mean follow-up was 25.5 ± 22 months. All the patients showed a good compliance to the device system with no complications (infections or skin erosions).

CONCLUSIONS

In complex CHD with already implanted PM devices, S-ICD implant appears to be a safe alternative to PM upgrading to transvenous ICD system, avoiding abandoned leads or life-threatening lead extraction. However, there are important issues with regard to testing and programming that need to be addressed at the time of implantation.

Subcutaneous Implantable Cardioverter-Defibrillators in Patients With Congenital Heart Disease

BACKGROUND

Very few data have been published on the use of subcutaneous implantable cardioverter-defibrillators (S-ICDs) in patients with congenital heart disease (CHD).

OBJECTIVES

The aim of this study was to analyze outcomes associated with S-ICDs in patients with CHD.

METHODS

This nationwide French cohort including all patients with an S-ICD was initiated in 2020 by the French Institute of Health and Medical Research. Characteristics at implantation and outcomes were analyzed in patients with CHD.

RESULTS

From October 12, 2012, to December 31, 2019, among 4,924 patients receiving an S-ICD implant in 150 centers, 101 (2.1%) had CHD. Tetralogy of Fallot, univentricular heart, and dextro-transposition of the great arteries represented almost one-half of the population. Patients with CHD were significantly younger (age 37.1 ± 15.4 years vs 50.1 ± 14.9 years; P < 0.001), more frequently female (37.6% vs 23.0%; P < 0.001), more likely to receive an S-ICD for secondary prevention (72.3% vs 35.9%; P < 0.001), and less likely to have severe systolic dysfunction of the systemic ventricle (28.1% vs 53.1%; P < 0.001). Over a mean follow-up period of 1.9 years, 16 (15.8%) patients with CHD received at least 1 appropriate shock, with all shocks successfully terminating the ventricular arrhythmia. The crude risk of appropriate S-ICD shock was twice as high in patients with CHD compared with non-CHD patients (annual incidences of 9.0% vs 4.4%; HR: 2.1; 95% CI: 1.3-3.4); however, this association was no longer significant after propensity matching (especially considering S-ICD indication, P = 0.12). The burden of all complications (HR: 1.2; 95% CI: 0.7-2.1; P = 0.4) and inappropriate shocks (HR: 0.9; 95% CI: 0.4-2.0; P = 0.9) was comparable in both groups.

CONCLUSIONS

In this nationwide study, patients with CHD represented 2% of all S-ICD implantations. Our findings emphasize the effectiveness and safety of S-ICD in this particularly high-risk population. (S-ICD French Cohort Study [HONEST]; NCT05302115).

Usefulness of the MADIT-ICD Benefit Score in a Large Mixed Patient Cohort of Primary Prevention of Sudden Cardiac Death

Background: Decision-making in primary prevention is not always trivial and many clinical scenarios are not reflected in current guidelines. To help evaluate a patient’s individual risk, a new score to predict the benefit of an implantable defibrillator (ICD) for primary prevention, the MADIT-ICD benefit score, has recently been proposed. The score tries to predict occurrence of ventricular arrhythmias and non-arrhythmic death based on data from four previous MADIT trials. We aimed at examining its usefulness in a large single-center register of S-ICD patients with various underlying cardiomyopathies. Methods and results: All S-ICD patients with a primary preventive indication for ICD implantation from our large single-center database were included in the analysis (n = 173). During a follow-up of 1227 ± 978 days, 27 patients developed sustained ventricular arrhythmias, while 6 patients died for non-arrhythmic reasons. There was a significant correlation for patients with ischemic cardiomyopathy (ICM) (n = 29, p = 0.04) to the occurrence of ventricular arrhythmia. However, the occurrence of ventricular arrhythmias could not sufficiently be predicted by the MADIT-ICD VT/VF score (p = 0.3) in patients with (n = 142, p = 0.19) as well as patients without structural heart disease (n = 31, p = 0.88) and patients with LV-EF < 35%. Of the risk factors included in the risk score calculation, only non-sustained ventricular tachycardias were significantly associated with sustained ventricular arrhythmias (p = 0.02). Of note, non-arrhythmic death could effectively be predicted by the proposed non-arrhythmic mortality score as part of the benefit score (p = 0.001, r = 0.3) also mainly driven by ICM patients. Age, diabetes mellitus, and a BMI < 23 kg/m2 were key predictors of non-arrhythmic death implemented in the score. Conclusion: The MADIT-ICD benefit score adds a new option to evaluate expected benefit of ICD implantation for primary prevention. In a large S-ICD cohort of primary prevention, the value of the score was limited to patients with ischemic cardiomyopathy. Future research should evaluate the performance of the score in different subgroups and compare it to other risk scores to assess its value for daily clinical practice.

Eligibility for subcutaneous implantable cardioverter-defibrillator in congenital heart disease

BACKGROUND

Adult congenital heart disease (ACHD) patients can benefit from a subcutaneous implantable cardioverter-defibrillator (S-ICD).

OBJECTIVE

The purpose of this study was to assess left- and right-sided S-ICD eligibility in ACHD patients, use machine learning to predict S-ICD eligibility in ACHD patients, and transform 12-lead electrocardiogram (ECG) to S-ICD 3-lead ECG, and vice versa.

METHODS

ACHD outpatients (n = 101; age 42 ± 14 years; 52% female; 85% white; left ventricular ejection fraction [LVEF] 56% ± 9%) were enrolled in a prospective study. Supine and standing 12-lead ECG were recorded simultaneously with a right- and left-sided S-ICD 3-lead ECG. Peak-to-peak QRS and T amplitudes; RR, PR, QT, QTc, and QRS intervals; Tmax, and R/Tmax (31 predictor variables) were tested. Model selection, training, and testing were performed using supine ECG datasets. Validation was performed using standing ECG datasets and an out-of-sample non-ACHD population (n = 68; age 54 ± 16 years; 54% female; 94% white; LVEF 61% ± 8%).

RESULTS

Forty percent of participants were ineligible for S-ICD. Tetralogy of Fallot patients passed right-sided screening (57%) more often than left-sided screening (21%; McNemar χ²P = .025). Female participants had greater odds of eligibility (adjusted odds ratio [OR] 5.9; 95% confidence interval [CI] 1.6-21.7; P = .008). Validation of the ridge models was satisfactory for standing left-sided (receiver operating characteristic area under the curve [ROC AUC] 0.687; 95% CI 0.582-0.791) and right-sided (ROC AUC 0.655; 95% CI 0.549-0.762) S-ICD eligibility prediction. Validation of transformation matrices showed satisfactory agreement (<0.1 mV difference).

CONCLUSION

Nearly half of the contemporary ACHD population is ineligible for S-ICD. The odds of S-ICD eligibility are greater for female than for male ACHD patients. Machine learning prediction of S-ICD eligibility can be used for screening of S-ICD candidates.

Narrative review of: risk stratification and implantable cardioverter-defibrillator therapy in adults with congenital heart disease

Fortunately, the population of adults with congenital heart disease (ACHD) is growing due to improved operation techniques. Life expectancy is continuously rising, nevertheless, sudden cardiac death is one of the leading causes of mortality in ACHD late after initial diagnosis. Risk stratification in ACHD remains challenging as large study results are missing, congenital defects and operation methods differ considerably between individual patients and results from acquired heart diseases are often not conferrable. The purpose of this narrative review is to objectively summarize the current knowledge on arrhythmogenic risk of ACHD and to give an overview on implantable cardioverter-defibrillator (ICD) therapy in this collective. Remarkable progress has been made in electrophysiological understanding of critical areas of slow conduction especially in patients with Tetralogy of Fallot (ToF). In patients with transposition of the great arteries after atrial baffling (Mustard/Senning procedure) atrial arrhythmias play a crucial role in sudden cardiac death. ICD therapy in ACHD may pose special technical challenges due to limited access for intracardiac leads. The introduction of the totally subcutaneous ICD improved therapeutic options for ACHD especially when contraindications for transvenous leads are present. Risk stratification in ACHD has to be seen as a team approach, requires thorough understanding of congenital heart defects and the operation techniques and needs unconventional technical approaches in some cases.

Subcutaneous implantable cardioverter defibrillator in children and adolescents: results from the S-ICD "Monaldi care" registry

BACKGROUND

Implantable cardioverter defibrillators (ICD) are widely accepted therapy in children and adolescents who are survivors of cardiac arrest or for high-risk patients with inheritable channelopathies, cardiomyopathies, or congenital heart disease. Initial experience with subcutaneous ICD (S-ICD) systems has shown a high efficacy in adults. However, the use of S-ICD in children and adolescents implies some specific considerations, as the safety for these patients is unknown and recommendations among physicians may vary widely.

METHODS

We reviewed the data and studied the indications for S-ICD in children and adolescents and discuss the preliminary clinical experience.

RESULTS

From a cohort of 297 patients enrolled in the S-ICD "Monaldi care" registry that encompass all the patients implanted in the Monaldi Hospital of Naples, we considered 21 consecutive children and adolescents (mean age 13.9 years, range 8-18 years, mean body weight 59.3 kg, range 38-100 kg) who underwent S-ICD implant from April 2014 to June 2020. Mean follow-up was 41.9±21.9 months. Only one patient presented, 6 weeks after implantation, skin erosion at the inferior parasternal incision that resolved after antibiotic therapy, without the necessity of any system revision. Two patients experienced appropriate shocks and four inappropriate shocks, due to T wave oversensing or atrial arrhythmia. Only one patient, with arrhythmogenic right ventricular dysplasia, required a system revision after 36 months of the first implantation and then a reintervention with a replacement of the S-ICD by a conventional ICD system.

CONCLUSIONS

Our experience suggests that the S-ICD device can be used in some children over the age of 8 as well as adults, with a similar rate of unwanted side effects, and early evidence of apparent efficacy.

Eligibility for subcutaneous implantable cardioverter-defibrillator in adults with congenital heart disease

Aims

Patients with adult congenital heart disease (ACHD) carry an increased risk for sudden cardiac death. Implantable cardioverter‐defibrillator (ICD) therapy may be challenging in these patients due to anatomical barriers, repeated cardiac surgery, or complicated transvenous access. Thus, the subcutaneous ICD (S‐ICD) can be a promising alternative in this patient population. Patients with ACHD show significant electrocardiogram (ECG) abnormalities, which could affect S‐ICD sensing because it depends on surface ECG.

Methods and results

One hundred patients with ACHD were screened for S‐ICD eligibility. Standard ECG‐based screening test and automated S‐ICD screening test were performed in all patients. Sixty‐six patients (66%) were male. Underlying congenital heart disease (CHD) was mainly CHD of great complexity (71%) and moderate complexity (29%), including repaired tetralogy of Fallot (20%), which was the most common entity. Thirty‐seven patients (37%) already had a pacemaker (23%) or ICD (14%) implanted. Automated screening test identified 83 patients (83%) eligible for S‐ICD implantation in either left parasternal position (78%) or right parasternal position (75%). Absence of sinus rhythm, QRS duration, and a paced QRS complex were associated with S‐ICD screening failure in univariate analysis. Receiver operating characteristic curve and multivariate analysis revealed a QRS duration ≥148 ms as the only independent predictor for S‐ICD screening failure.

Conclusions

Patients with ACHD show satisfactory eligibility rates (83%) for S‐ICD implantation utilizing the automated screening test, including patients with CHD of high complexity. S‐ICD therapy should be considered with caution in ACHD patients with a QRS duration ≥148 ms and/or need for ventricular pacing.