A Single Center Prospective Study in an Estimated 570 Patients Who Underwent Genetic Screening at UZ Brussel in the Context of a Primary Cardiac Arrhythmia. Patients Showing a Variant Class 3,4 or 5 in SCN4A or CLCN1 Will Undergo a Clinical and Electrophysiological Review After IC.

NCT07183059 | Not Yet Recruiting

• 1 other identifier: 25255_NDM-PCA studie
• Study Type: interventional
• Target: 570
• Locations: 0 countries
• Sites: N/A

Brief Summary

A prospective interventional single-center study will be conducted. The study includes clinically diagnosed Intramuros PCA-patients who underwent a PCA gene panel of 113 genes (see Appendix 1) in the UZ-Brussel since 2021. In a retrospective part of the study, we will assess cardiac history, cardiac family history, cardiac exams and medical treatment and genetic data and family history. The prevalence of a class 3, 4 or 5 variant in the SCN4A and CLCN1 gene in the PCA-group will be compared to controls who underwent genetic screening for different causes, in which no association with muscular channelopathies is expected, without access to their medical file. In a prospective part of the study, patients with PCA carrying a variant class 3,4 or 5 in the SCN4A gene or a variant class 3, 4 or 5 in the CLCN1 gene will be invited for a one day visit for an interview, clinical neurological assessment and EMG. The aim of this second phase is to describe the clinical presentation of patients with concomitant PCA and non-dystrophic myotonia .

Conditions

Non Dystrophic Myotonia; Arrythmia, Cardiac

Outcome Measures

Primary Outcomes (2)

• Prevalence of variants of class 3,4 or 5 in the SCN4A gene and variants of class 3, 4 or 5 in het CLCN1 gene in patients presenting with PCA.

  the prevalence of variants of class 3,4 or 5 in the SCN4A gene and variants of class 3, 4 or 5 in het CLCN1 gene in patients presenting with PCA compared to a control group

  Day 1

• Clinical presentation of NDMs in patients presenting with PCA and class 3,4 or 5 variants in SCN4A or CLCN1 gene.

  the clinical presentation of NDMs in patients presenting with PCA and class 3,4 or 5 variants in SCN4A or CLCN1 gene.

  Day 1

Study Arms (1)

Exploring overlap between primary cardiac arrhythmi-as and non-dystrophic myotonia: a single center

EXPERIMENTAL

Patients with PCA carrying a variant class 3,4 or 5 in the SCN4A gene or a variant class 3, 4 or 5 in the CLCN1 gene will be invited by the department of Medical Genetics where they already have had a consultation, to the Neurology department for one visit on one day for the following as-sessments: * Interview to assess the presence, onset and duration of myotonia or episodic weakness. Assessment of medical history, family history and medical treatment. * Clinical neurological assessment for clinical myotonia. * Electromyography (EMG) to detect the presence of myotonic discharges and using the Streib and Sun score for quantification(34). * Short exercise test in case of myotonic discharges on nEMG. * In case of a diagnosis of a muscular channelopathy, assessment with.a QoL scale.

Diagnostic Test: Electromyography

Interventions

Electromyography DIAGNOSTIC_TEST

we will perform questionnaire, clinical neurological exam, nEMG and if applicable short exercise test on patients with variants in genes associated with mus-cular channelopathies. Safety Monitoring and reporting: Needle EMG is generally well-tolerated, but transient mild proce-dural pain and discomfort are widespread and the most frequent side effect that patients will ex-perience. Hematomas are infrequent and, in most cases, asymptomatic and selflimiting. Moreover, the bleeding risk is reduced by the investigator's experience, testing superficial muscles (avoiding complications like compartment syndrome), and by not conducting an EMG when patient is treated with anticoagulants. Infectious complications at the site of needle insertion are extremely infre-quent since disposable needle electrodes are used. Needle insertion is avoided in in-jured/potential infected skin and will not be performed in immune-compromised patients and endocarditis risk.

Exploring overlap between primary cardiac arrhythmi-as and non-dystrophic myotonia: a single center

Eligibility Criteria

• Age: 18 Years - 100 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Patients with PCA who underwent a genetic analysis with a PCA gene panel since 2021 (since the panel involves 112 genes including SCN4A).
• Male and female gender.

You may not qualify if:

• Genetic analysis before 2021
• Patients without cardiac screening in UZ Brussel

Sponsors & Collaborators

• Universitair Ziekenhuis Brussel: lead

MeSH Terms

Conditions

Arrhythmias, Cardiac

Interventions

Electromyography

Condition Hierarchy (Ancestors)

Heart Diseases; Cardiovascular Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Electrodiagnosis; Diagnostic Techniques and Procedures; Diagnosis; Myography

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: DIAGNOSTIC
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 4, 2025
• First Posted: September 19, 2025
• Study Start: December 15, 2025
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): September 30, 2027
• Last Updated: December 1, 2025

Record last verified: 2025-08