Clinical
Eligibility for subcutaneous implantable cardioverter-defibrillator in congenital heart disease

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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 χ2 P = .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.

Introduction

A subcutaneous implantable cardioverter-defibrillator (S-ICD) is a lifesaving device that prevents sudden cardiac arrest in vulnerable patients.1 Approval of use of the S-ICD in the United States is significant because of its benefits over the traditional transvenous ICD; such benefits include the lack of risk for vascular occlusion, systemic infection, and adverse effects of lead extraction. The S-ICD can be especially advantageous in adult congenital heart disease (ACHD) patients, who may have limited or no venous access to the heart and who have an increased risk of systemic embolism when a persistent shunt is present.2,3 These individuals are often at increased risk for sudden cardiac arrest that is higher in ACHD patients compared to the general population4 and frequently require thoracic surgery for insertion of an epicardial ICD system. ACHD patients may face multiple generator changes in their lifetime, making an S-ICD a viable option because of its less invasive placement. The 2017 American Heart Association/American College of Cardiology/ Heart Rhythm Society guideline for the prevention of sudden cardiac arrest in ACHD patients recommend S-ICD use when feasible.5

S-ICD requires electrocardiographic (ECG) prescreening before implantation to assess sensing. S-ICD prescreening involves recording a special 3-lead ECG with ECG electrodes placed in the locations of S-ICD sensing electrodes.6 This additional step may negatively impact the utilization of S-ICD.7 Lack of confidence is the most common barrier for referral among physicians,8 and the perceived strength of the physician recommendation is the most common theme associated with ICD refusal among primary prevention candidates.9 Conversely, a 12-lead ECG is readily available and easy to obtain. Therefore, using a conventional 12-lead ECG as the tool for prescreening eligibility would greatly improve a physician’s confidence in referral to an electrophysiologist and recommendation to suitable patients.

Our group recently developed a screening tool to predict left-sided S-ICD eligibility from a 12-lead ECG,10 although validation of this screening tool in an out-of-sample population has not been performed. Moreover, right-sided S-ICD implantation may improve S-ICD eligibility among ACHD patients.11 However, few data are available regarding right-sided S-ICD eligibility predictors in ACHD patients. Furthermore, whether it is feasible to transform the 12-lead ECG into left-and right-sided S-ICD 3-lead ECG, and vice versa, remains unknown.

We conducted this study with several goals: (1) to assess left- and right-sided S-ICD eligibility in ACHD patients; (2) to validate the previous left-sided S-ICD eligibility prediction tool10; (3) to use machine learning to predict right- and left-sided S-ICD eligibility in ACHD patients; and (4) to develop and validate transformation matrices to transform 12-lead ECG to S-ICD 3-lead ECG, and vice versa.

Section snippets

Methods

MATLAB (MathWorks, Inc, Natick, MA) open source code for ECG analyses, a user manual, and fully de-identified raw digital ECG signal data are available at https://github.com/Tereshchenkolab/S-ICD_eligibility.

Study population

A total of 101 ACHD patients were recruited (Table 1). Most of the study participants had moderate or severe complexity ACHD with hemodynamic impairment and, on average, borderline systemic ventricular function. Participants had a history of Fontan, Ross, Mustard, Senning, Rastelli, Glenn, Damus-Kaye-Sensel, and Norwood procedures. Nearly every fifth study participant already had a transvenous cardiac device implanted, more likely an ICD (65%) than a pacemaker (35%). Approximately two-thirds of

Discussion

This prospective study of the contemporary ACHD population revealed several important findings. First, we observed a high rate of S-ICD ineligibility: nearly half of ACHD patients were not eligible for S-ICD. Second, we noted sex differences: odds of S-ICD eligibility were nearly six 6-greater for female compared to male ACHD patients. The high rate of S-ICD ineligibility in the ACHD population represents a significant barrier for the adoption of potentially advantageous and less invasive S-ICD

Acknowledgments

The authors thank the study participants and staff. We thank Christopher Hamilton, BA, and Meghan Hisatomi Saito, ACNP, for help with ECG recording and enrollment.

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    This research was supported in part by National Institutes of Health Grant HL118277 to Dr Tereshchenko and the Boston-Scientific Center for the Advancement of Research to Dr Tereshchenko. This physician-initiated study (PI Tereshchenko) was partially supported by the Boston-Scientific Center for the Advancement of Research. The Boston Scientific company had no role in the design, execution, analyses, and interpretation of the data and results of this study. ClinicalTrials.gov Identifier: NCT03209726.

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