Measurement of the Electromechanical Window to Improve the Diagnosis of Congenital Long QT Syndrome (FEMQT)

The goal of this research is to prospectively evaluate the performance of the electromechanical window according to a phonographic method, as a mean of diagnosis of long QT syndrome, and to compare its performance with routine tests used.

Study Overview

• Status: Completed
• Conditions: Long QT Syndrome
• Intervention / Treatment: Diagnostic test: ECG coupled to phonocardiography

Detailed Description

Familial long QT syndrome (LQTS) is a hereditary cardiac disorder in which most affected family members have delayed ventricular repolarization manifest on the electrocardiogram (ECG) as QT prolongation. This disease is associated with an increased propensity to palpitations, syncope, polymorphous ventricular tachycardia and sudden arrhythmic death. The diagnosis relies mostly on resting ECG findings and on genetic testing. In clinical practice however, this diagnosis is complicated by 2 main reasons: 1) a significant overlap in ECG findings between healthy and diseased individuals and 2) a frequent identification of genetic variants of unknown significance. Recent studies have suggested that echocardiographic measurement of the electromechanical window (EMW - the delay between the end of mechanical contraction and electrical activation of the heart) has better performance in the diagnosis of LQTS. The echocardiographic technique is however too complicated for routine clinical use. Preliminary work conducted at the University Hospital of Bordeaux and at the University Hospital of Reunion Island has demonstrated that a phonocardiographic approach leads to similar results with an improved feasibility and a good reproducibility.

• Study Type: Interventional
• Enrollment (Actual): 224
• Phase: Not Applicable

Contacts and Locations

Study Locations

• France
  • Nantes, France, 44093
    • Nantes University Hospital
  • Pessac, France, 33604
    • Bordeaux University Hospital
  • Saint-Pierre, France, 97410
    • La Réunion University Hospital
  • Toulouse, France, 31400
    • Toulouse University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 8 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Propositus patients with genetically proven LQTS and their relatives,
• Patients of both sexes aged 12 and over,
• Free, informed and written consent of the patient and the two holders of parental authority for minors.

Exclusion Criteria:

• Inability to consent,
• Person deprived of liberty by judicial or administrative decision,
• Majors subject to a legal protection measure,
• Person participating in another research including an exclusion period still in progress,
• Severely impaired physical and / or psychological health, which, according to the investigator, may affect the participant's compliance with the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Prospective FEMQT Group; Propositus patients with genetically proven LQTS and their relatives

Diagnostic test: ECG coupled to phonocardiography; A standard ECG is recorded along with a phonocardiographic recording. The phonocardiographic recording is obtained by using a specific electronic stethoscope plugged into the auxiliary port of the ECG machine. The recording takes less than 30 seconds. The two recording methods are concomitant. QT interval is measured on the ECG recording, EMW is measured with ECG coupled to phonocardiography.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Negative predictive value (NPV) obtained by the two methods of diagnosis	The NPV is measured in percentage. The NPV of LQTS diagnosis obtained by phonocardiographic method (measurement of the EMW) and the NPV obtained by standard ECG method (QT measurement prolongation) will be compared.	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Values of sensitivity obtained by the two methods of diagnosis	Value of sensitivity is measured in percentage. The values of sensitivity of EMW and standard ECG will be compared.	Day 1
Values of specificity obtained by the two methods of diagnosis	Value of specificity is measured in percentage. The values of specificity of EMW and standard ECG will be compared.	Day 1
Positive predictive values obtained by the two methods of diagnosis	Positive predictive value is measured in percentage. Positive predictive values of EMW and standard ECG will be compared.	Day 1
Area Under the Curves (AUC) obtained by the two methods of diagnosis	The AUC obtained by Receiver Operating Characteristic (ROC) analyses is measured by a value between 0 and 1. The AUC obtained by ROC of EMW and standard ECG will be compared.	Day 1

Collaborators and Investigators

• Sponsor: University Hospital, Bordeaux
• Investigators: Principal Investigator: Josselin DUCHATEAU, MD, University Hospital, Bordeaux

Study record dates

Study Major Dates

• Study Start (Actual): August 28, 2020
• Primary Completion (Actual): April 23, 2024
• Study Completion (Actual): April 23, 2024

Study Registration Dates

• First Submitted: March 27, 2020
• First Submitted That Met QC Criteria: March 27, 2020
• First Posted (Actual): March 31, 2020

Study Record Updates

• Last Update Posted (Actual): June 17, 2025
• Last Update Submitted That Met QC Criteria: June 12, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Long QT syndrome; Electromechanical window; Phonocardiography
• Additional Relevant MeSH Terms: Cardiac Conduction System Disease; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Disease; Arrhythmias, Cardiac; Congenital Abnormalities; Cardiovascular Abnormalities; Heart Defects, Congenital; Syndrome; Long QT Syndrome
• Other Study ID Numbers: CHUBX 2019/35

Drug and device information, study documents

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