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.
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)
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)
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).
Cohort
Prospective
Subcutaneous ICD ECG screening
Diagnostic testSurface 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.
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.
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.
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.
Eligibility according to electrode position
Proportion of participants eligible for the subcutaneous ICD in each screening electrode position.
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.
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.
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