Conventional and right-sided screening for subcutaneous ICD in a population with congenital heart disease at high risk of sudden cardiac death

Subcutaneous Implantable Cardioverter Defibrillators in Pediatrics and Congenital Heart Disease

Subcutaneous implantable cardioverter defibrillators (S-ICDs) are being used with increased frequency in children and patients with congenital heart disease. Vascular access complexities, intracardiac shunts, and specific anatomies make these devices particularly appealing for some of these patients. Alternative screening, implantation, and programming techniques should be considered based on patient size, body habitus, anatomy, procedural history, and preference. Appropriate and inappropriate shock rates are generally comparable to those seen with transvenous devices. Complications such as infection can occur, although their severity is likely to be less than that seen with transvenous devices. Technical advances are likely to further broaden S-ICD applicability.

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.

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.

Comparing the safety of subcutaneous versus transvenous ICDs: a meta-analysis

PURPOSE

The use of transvenous implantable cardioverter defibrillators (TV-ICDs) is associated with multiple risks related to the presence of the defibrillator leads within the venous system and right side of the heart, including endocarditis, venous occlusion, tricuspid regurgitation, and potential lead failure. The emergence of subcutaneous ICDs (S-ICDs) may potentially overcome the aforementioned disadvantages. However, evidence validating the safety of S-ICDs relative to TV-ICDs is limited. The present study aimed to synthesize and analyze available data from published studies to comprehensively compare transvenous and subcutaneous ICDs.

METHODS

Different databases were searched for full-text publications with a direct comparison of TV- and S-ICDs. Fixed effect models were applied to pooled data, and no study-to-study heterogeneity was detected.

RESULTS

Data from 7 studies totaling 1666 patients were pooled together. Compared to S-ICDs, the risk of suffering device-related complications was higher in patients with TV-ICDs (OR = 1.71; 95% CI: 1.23-2.38). The number of patients with an S-ICD who suffered inappropriate shocks (IS) was not significantly different than patients with a TV-ICD (OR = 0.92; 95% CI: 0.65-1.30). Subgroup analysis indicated that the TV-ICD group had a higher risk of IS due to supraventricular oversensing (OR = 3.29; 95% CI: 1.92-5.63) while T-wave oversensing tending to cause IS in the S-ICD group (OR = 0.09; 95% CI: 0.03-0.23). The risk of device-related infection in the S-ICD group was not any lower than that in the TV-ICD group (OR = 1.57; 95% CI: 0.67-3.68). The survival rate without any complications during a 1-year follow-up period was similar between the 2 groups (HR = 1.23; 95% CI: 0.81-1.86), although it was assumed that the trend leaned toward more complications in patients with a TV-ICD.

CONCLUSION

The present study verified the safety of S-ICDs based on pooled data. Although there were no differences between TV- and S-ICDs in the short term, fewer adverse events were found in patients with S-ICDs during long-term follow-up.

Adults with Congenital Heart Disease and Arrhythmia Management

Arrhythmia management in adult congenital heart disease (ACHD) encompasses a wide range of problems from bradyarrhythmia to tachyarrhythmia, sudden death, and heart failure-related electrical dyssynchrony. Major advances in the understanding of the pathophysiology and treatments of these problems over the past decade have resulted in improved therapeutic strategies and outcomes. This article attempts to define these problems and review contemporary management for the patient with ACHD presenting with cardiac arrhythmia.

Impact of routine right parasternal electrocardiographic screening in assessing eligibility for subcutaneous implantable cardioverter-defibrillator

INTRODUCTION

Between 7% and 15% of patients with an indication for an implantable cardioverter-defibrillator (ICD) are not eligible for implantation of a subcutaneous implantable cardioverter-defibrillator (S-ICD) on the basis of the result of the conventional left parasternal electrocardiographic screening (LPES). Our objective was to determine the impact of systematically performing right parasternal electrocardiographic screening (RPES) in addition to conventional LPES, in terms of increasing both the total percentage of potentially eligible patients for S-ICD implantation and the number of suitable vectors per patient.

METHODS AND RESULTS

Consecutive patients from the outpatient device clinic who already had an implanted ICD, and no requirement for pacing were enrolled. Conventional left parasternal electrode position and right parasternal electrode positions were used. The automatic screening tool was used to analyze the recordings. Screenings were performed in the supine and standing positions. Overall, 209 patients were included. The mean age was 63.4 ± 13 years, 59.8% had ischemic heart disease, mean QRS duration was 100 ± 31 ms, and 69.9% had a primary prevention ICD indication. Based on conventional isolated LPES, 12.9% of patients were not eligible for S-ICD compared with 11.5% based on RPES alone (P = .664). Considering LPES and RPES together, only 7.2% of patients were not eligible for S-ICD (P < .001). Moreover, the number of patients with more than one suitable vector increased from 66.5% with isolated LPES to 82.3% (23.7% absolute increase [P < .001]).

CONCLUSION

Adding an automated RPES to the conventional automated LPES increased patient eligibility for the S-ICD significantly. Moreover, combined screening increased the number of suitable vectors per eligible patient.

The utility of routine clinical 12-lead ECG in assessing eligibility for subcutaneous implantable cardioverter defibrillator

INTRODUCTION

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a life-saving device. Recording of a specialized 3-lead electrocardiogram (ECG) is required for S-ICD eligibility assessment. The goals of this study were: (1) evaluate the effect of ECG filtering on S-ICD eligibility, and (2) simplify S-ICD eligibility assessment by development of an S-ICD ineligibility prediction tool, which utilizes the widely available routine 12-lead ECG.

METHODS AND RESULTS

Prospective cross-sectional study participants [n = 68; 54% male; 94% white, with wide ranges of age (18-81 y), body mass index (19-53), QRS duration (66-150 ms), and left ventricular ejection fraction (37-77%)] underwent 12-lead supine, 3-lead supine and standing ECG recording. All 3-lead ECG recordings were assessed using the standard S-ICD pre-implantation ECG morphology screening. Backward, stepwise, logistic regression was used to build a model for 12-lead prediction of S-ICD eligibility. Select electrocardiogram waves and complexes: QRS, R-, S, and T-amplitudes on all 12 leads, averaged QT interval, QRS duration, and R/T ratio in the lead with the largest T wave (R/T_max) were included as predictors. The effect of ECG filtering on ECG morphology was evaluated. A total of 9 participants (13%) failed S-ICD screening prior to filtering. Filtering at 3-40 Hz, similar to the S-ICD default, reduced S-ICD ineligibility to 4%. A regression model that included R_II, S_II-aVL, T_{I, II, aVL, aVF, V3-V6}, and R/T_max perfectly predicted S-ICD eligibility, with an Area Under the Receiver Operating Characteristic Curve of 1.0.

CONCLUSION

Routine clinical 12-lead ECG can be used to predict S-ICD eligibility. ECG filtering may improve S-ICD eligibility.

Conventional and right-sided screening for subcutaneous ICD in a population with congenital heart disease at high risk of sudden cardiac death

BACKGROUND

Information regarding suitability for subcutaneous defibrillator (sICD) implantation in tetralogy of Fallot (ToF) and systemic right ventricle is scarce and needs to be further explored. The main objective of our study was to determine the proportion of patients with ToF and systemic right ventricle eligible for sICD with both, standard and right-sided screening methods. Secondary objectives were: (i) to study sICD eligibility specifically in patients at high risk of sudden cardiac death, (ii) to identify independent predictors for sICD eligibility, and (iii) to compare the proportion of eligible patients in a nonselected ICD population.

METHODS

We recruited 102 patients with ToF, 33 with systemic right ventricle, and 40 consecutive nonselected patients. Conventional electrocardiographic screening was performed as usual. Right-sided alternative screening was studied by positioning the left-arm and right-arm electrodes 1 cm right lateral of the xiphoid midline. The Boston Scientific ECG screening tool was utilized.

RESULTS

In high-risk patients with ToF, eligibility was higher with right-sided screening in comparison with standard screening (61% vs. 44%; p = .018). Eligibility in high-risk right ventricle population was identical with both screening methods (77%, p = ns). The only independent predictor for sICD eligibility was QRS duration.

CONCLUSION

In high-risk patients with ToF, right-sided implantation of the sICD could be an alternative to a conventional ICD. In patients with a systemic right ventricle, implantation of a sICD is an alternative to a conventional sICD.