Subcutaneous Implantable Cardioverter-defibrillator (S-ICD) Eligibility Over Time in Arrhythmogenic Cardiomyopathy

Evaluation of Subcutaneous Implantable Cardioverter-defibrillator Eligibility in Patients With Arrhythmogenic Right and Left Ventricular Cardiomyopathy: a Prospective Longitudinal Pilot Cohort Study

The goal of this observational study is to learn whether adults with arrhythmogenic cardiomyopathy, an inherited heart muscle disease that can cause dangerous heart rhythms, remain eligible for a subcutaneous implantable cardioverter-defibrillator (S-ICD) over time.

An S-ICD is a device placed under the skin, outside the heart, that can stop life-threatening heart rhythms with an electric shock. Before an S-ICD is implanted, a screening test checks whether the heart's electrical signals, recorded from the skin of the chest, are suitable for the device to work correctly. Because arrhythmogenic cardiomyopathy is a progressive disease, these signals may change over time, and a patient who passes the screening today may not pass it later.

The main questions it aims to answer are:

• Does S-ICD eligibility remain stable over 18 months in patients with arrhythmogenic cardiomyopathy?
• Are changes in eligibility related to changes in the electrocardiogram during follow-up?

Researchers will compare patients with arrhythmogenic cardiomyopathy with patients with Brugada syndrome, a condition in which the S-ICD is commonly used, and with people without structural heart disease.

Participants will:

• Undergo S-ICD screening using the manufacturer's screening algorithm, with electrodes placed on the chest skin, at the start of the study and again at 6, 12 and 18 months
• Continue their usual medical care

No device will be implanted as part of this study. Any decision to implant a defibrillator will be made by each patient's care team, independently of the study.

Study Overview

• Status: Recruiting
• Conditions: Arrhythmogenic Cardiomyopathy
• Intervention / Treatment: Diagnostic test: Subcutaneous ICD ECG screening

Detailed Description

Background: Arrhythmogenic cardiomyopathy (ACM) is a genetic, progressive heart muscle disease characterized by fibrofatty replacement of the myocardium, which predisposes patients to ventricular arrhythmias, heart failure and sudden cardiac death. The disease was initially described as a predominantly right ventricular condition (arrhythmogenic right ventricular cardiomyopathy, ARVC), diagnosed by the 2010 Task Force criteria, but left ventricular and biventricular involvement are now recognized, were proposed to incorporate left ventricular manifestations (arrhythmogenic left ventricular cardiomyopathy, ALVC). In high-risk patients, an implantable cardioverter-defibrillator (ICD) is recommended for the prevention of sudden cardiac death.

The subcutaneous ICD (S-ICD) is an entirely extravascular alternative that avoids transvenous leads and their long-term complications. However, S-ICD candidates must undergo pre-implant surface electrocardiogram (ECG) screening to ensure appropriate sensing and to reduce the risk of inappropriate shocks due to T-wave oversensing. Because ACM is progressive, its characteristic depolarization and repolarization abnormalities (such as T-wave inversion, epsilon waves, low QRS voltage and conduction delay) may change over time and affect S-ICD eligibility after an initially favorable screening. Data on the performance and long-term eligibility of the S-ICD in this population remain scarce.

Study design: This is a prospective, longitudinal, single-center pilot cohort study conducted at the Arrhythmia Clinical Unit of the Heart Institute (InCor), Hospital das Clínicas, University of São Paulo Medical School, Brazil. The study includes three groups of 30 participants each: patients with ACM (study group); patients with Brugada syndrome, a condition in which the S-ICD is commonly indicated (reference group); and individuals without structural heart disease on transthoracic echocardiography (control group).

Study procedures: After informed consent, S-ICD eligibility is assessed using the LATITUDE programmer (Boston Scientific) and the manufacturer's screening algorithm, with surface ECG electrodes placed in the standard screening positions on the chest. Skin preparation may include shaving of chest hair and cleaning with alcohol. The screening is the only study procedure and is repeated at 6, 12 and 18 months after the baseline assessment, regardless of whether a device has been implanted. The study does not involve device implantation, device supply or any change in clinical management; implantation decisions remain at the discretion of each patient's care team.

Statistical analysis: Continuous variables will be described as means and standard deviations or medians and interquartile ranges, and categorical variables as absolute and relative frequencies. The proportion of patients eligible for the S-ICD at baseline and at each follow-up visit will be estimated with 95% confidence intervals and compared using logistic regression. Differences in the number of eligible sensing vectors between time points will be assessed by paired t-test or Wilcoxon signed-rank test, as appropriate, and eligibility across electrode positions will be compared using logistic regression for repeated measures. Factors associated with eligibility and loss of eligibility will be explored using Student's t-test or Mann-Whitney test for continuous variables and Pearson's chi-square or Fisher's exact test for categorical variables. Exploratory multivariable logistic regression models may be fitted, considering the limited sample size, with results reported as odds ratios and 95% confidence intervals. A two-sided significance level of 5% will be adopted.

• Study Type: Observational
• Enrollment (Estimated): 90

Contacts and Locations

• Study Contact: Name: Luciana Sacilotto, MD, PhD; Phone Number: 551126615342; Email: lu.sacilotto@gmail.com

Study Locations

• Brazil
  • São Paulo
    • São Paulo, São Paulo, Brazil, 05403-900
      • Recruiting
      • Heart Institute
      • Contact: Luciana Sacilotto, MD, PhD; Phone Number: 551126615342; Email: lu.sacilotto@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Adults followed at the Arrhythmia Clinical Unit of the Heart Institute (InCor), Hospital das Clínicas, University of São Paulo Medical School, São Paulo, Brazil, in three groups: patients with arrhythmogenic right or left ventricular cardiomyopathy; patients with Brugada syndrome, a condition in which the subcutaneous ICD is commonly indicated (reference group); and individuals without structural heart disease on transthoracic echocardiography (control group).

Description

Arrhythmogenic cardiomyopathy group

Inclusion Criteria:

• Age 18 years or older
• Diagnosis of arrhythmogenic right ventricular cardiomyopathy according to the updated 2010 Task Force criteria, or arrhythmogenic left ventricular cardiomyopathy according to the Padua criteria
• Risk stratification for primary prevention of sudden cardiac death using the ARVC risk calculator (<5% = low risk; 5% to 10% = intermediate risk; >10% = high risk) or the 2015 International Task Force consensus; or secondary prevention (documented ventricular tachycardia or resuscitated cardiac arrest)

Exclusion Criteria:

• Ventricular pacing by an artificial pacemaker
• Heart transplantation
• Refusal to sign the informed consent form
• Comorbidities with a life expectancy of less than 1 year (e.g., advanced malignancy)

Brugada syndrome reference group

Inclusion Criteria:

• Age 18 years or older
• Type 1 Brugada ECG pattern, spontaneous or drug-induced

Exclusion Criteria:

• Ventricular pacing by an artificial pacemaker
• Heart transplantation
• Refusal to sign the informed consent form
• Comorbidities with a life expectancy of less than 1 year (e.g., advanced malignancy)

Control group

Inclusion Criteria:

• Age 18 years or older
• No structural heart disease, defined by a transthoracic echocardiogram with all parameters within normal reference values

Exclusion Criteria:

• Structural heart disease on transthoracic echocardiography
• Ventricular pacing by an artificial pacemaker
• Heart transplantation
• Refusal to sign the informed consent form
• Comorbidities with a life expectancy of less than 1 year (e.g., advanced malignancy)

Study Plan

How is the study designed?

Design Details

• Observational Models: COHORT
• Time Perspectives: PROSPECTIVE

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Arrhythmogenic cardiomyopathy; Adults with arrhythmogenic right ventricular cardiomyopathy (2010 Task Force criteria) or arrhythmogenic left ventricular cardiomyopathy (Padua criteria), with an indication for an implantable cardioverter-defibrillator for primary or secondary prevention of sudden cardiac death, followed at the Arrhythmia Clinical Unit of InCor.	Diagnostic test: Subcutaneous ICD ECG screening; Surface ECG screening for subcutaneous implantable cardioverter-defibrillator eligibility using the manufacturer's screening algorithm, performed at baseline and at 6, 12 and 18 months. No device is implanted as part of the study.
Brugada syndrome (reference group); Adults with type 1 Brugada ECG pattern, spontaneous or drug-induced, a condition in which the subcutaneous ICD is commonly indicated.	Diagnostic test: Subcutaneous ICD ECG screening; Surface ECG screening for subcutaneous implantable cardioverter-defibrillator eligibility using the manufacturer's screening algorithm, performed at baseline and at 6, 12 and 18 months. No device is implanted as part of the study.
Control group; Adults without structural heart disease, defined by a normal transthoracic echocardiogram.	Diagnostic test: Subcutaneous ICD ECG screening; Surface ECG screening for subcutaneous implantable cardioverter-defibrillator eligibility using the manufacturer's screening algorithm, performed at baseline and at 6, 12 and 18 months. No device is implanted as part of the study.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stability of subcutaneous ICD eligibility over 18 months	Proportion of patients with arrhythmogenic cardiomyopathy who are eligible for a subcutaneous implantable cardioverter-defibrillator at each assessment, and proportion of those eligible at baseline who remain eligible during follow-up. Eligibility is determined by surface ECG screening using the manufacturer's screening algorithm.	Baseline, 6, 12 and 18 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Association between ECG changes and subcutaneous ICD eligibility at 18 months	Correlation between changes in surface ECG parameters during follow-up and subcutaneous ICD eligibility at 18 months in patients with arrhythmogenic cardiomyopathy.	Baseline to 18 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of eligible sensing vectors	Change in the number of sensing vectors that pass the subcutaneous ICD screening between baseline and each follow-up assessment.	Baseline, 6, 12 and 18 months
Eligibility according to electrode position	Proportion of participants eligible for the subcutaneous ICD in each screening electrode position.	Baseline, 6, 12 and 18 months
Comparison of subcutaneous ICD eligibility among study groups	Proportion of participants eligible for the subcutaneous ICD in the arrhythmogenic cardiomyopathy group compared with the Brugada syndrome reference group and the control group.	Baseline, 6, 12 and 18 months
Clinical factors associated with loss of subcutaneous ICD eligibility	Clinical, electrocardiographic and imaging characteristics associated with loss of subcutaneous ICD eligibility during follow-up, reported as odds ratios with 95% confidence intervals.	Baseline to 18 months

Collaborators and Investigators

• Sponsor: University of Sao Paulo

Study record dates

Study Major Dates

• Study Start (Actual): July 8, 2026
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): July 1, 2028

Study Registration Dates

• First Submitted: September 24, 2026
• First Submitted That Met QC Criteria: September 24, 2026
• First Posted (Actual): September 30, 2026

Study Record Updates

• Last Update Posted (Actual): October 5, 2026
• Last Update Submitted That Met QC Criteria: October 1, 2026
• Last Verified: October 1, 2026

More Information

Terms related to this study

• Keywords: Arrhythmogenic cardiomyopathy
• Other Study ID Numbers: 98034926.8.0000.0068; 8.499.814 (Other Identifier: Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No