MCG In Long QT Syndrome

Magnetocardiography in Long QT Syndrome: A Prospective Study of Its Clinical and Prognostic Utility

The primary objective of this observational study is to evaluate whether magnetocardiography (MCG) findings more accurately predict clinical outcomes in patients with acquired Long QT syndrome compared to ECG. The secondary objective is to assess differences in QT interval length between MCG and ECG. The primary safety objective is to characterize the safety profile of the CardiAQ MCG device.

Study Overview

• Status: Not yet recruiting
• Conditions: Atrial Fibrillation
• Intervention / Treatment: Diagnostic test: Magnetocardiography

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

• Study Contact: Name: Patsy Caceres Figueroa; Phone Number: 507-266-3054; Email: caceresfigueroa.patsy@mayo.edu

Study Locations

• United States
  • Minnesota
    • Rochester, Minnesota, United States, 55905
      • Mayo Clinic in Rochester
      • Principal Investigator: Mohamad Alkhouli, MD
      • Contact: Structural Heart Research Team; Phone Number: (507) 255-6133

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Study candidates may be identified and recruited in one of the following ways:

• In-patient service at the study institution.
• From the Principal Investigator or Co-Investigator clinical practices
• Referral from other hospitals
• Cardiology Specialty Clinics

Description

Inclusion Criteria

1. Age ≥ 18 years on the date of consent
2. Ability for participant to comply with study requirements
3. Written informed consent
4. Confirmed diagnosis of atrial fibrillation and receiving dofetilide for rhythm control in the inpatient setting.

Exclusion Criteria

1. Pregnant or breastfeeding
2. Active thoracic metal implants (including pacemaker, insertable cardiac monitor, or internal defibrillators).
3. External electrical pads or devices (e.g. Pacer pads, ECG electrodes, heart rate patch), that must remain on patient's chest during MCG scan
4. Inability to lie down in a supine/inclined position and stay still on the examination bed
5. Clinical conditions that in the opinion of the Investigator would compromise the safety of the patient or ability to complete the protocol

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Subjects diagnosed with atrial fibrillation	Diagnostic test: Magnetocardiography; MCG is a non-invasive, radiation-free imaging technique that detects the magnetic field generated by the electrical activity of the heart.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of successful dofetilide loading using Magnetocardiography	Dofetilide loading is considered successful if the following conditions are met: No excessive QTc prolongation QTc remains <500 ms, and no >15% increase from baseline.; No sustained VT or recurrent/symptomatic non-sustained VT (NSVT) suggestive of proarrhythmia.; No symptomatic bradycardia or hemodynamic instability; Stable renal function; No deterioration necessitating dose reduction or discontinuation.; Discharge on a stable dose	Baseline
Number of successful dofetilide loading using Electrocardiogram	Dofetilide loading is considered successful if the following conditions are met: No excessive QTc prolongation QTc remains <500 ms, and no >15% increase from baseline.; No sustained VT or recurrent/symptomatic non-sustained VT (NSVT) suggestive of proarrhythmia.; No symptomatic bradycardia or hemodynamic instability; Stable renal function; No deterioration necessitating dose reduction or discontinuation.; Discharge on a stable dose	Baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Magnetocardiography - QT interval length	QT interval length is a measurement from the start of the Q wave to the end of the T wave. This will be measured in seconds.	Baseline
Electrocardiogram - QT interval length	QT interval length is a measurement from the start of the Q wave to the end of the T wave. This will be measured in seconds.	Baseline

Collaborators and Investigators

• Sponsor: Mayo Clinic
• Investigators: Principal Investigator: Mohamad Alkhouli, M.D., M.B.A., Mayo Clinic

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: November 25, 2025
• First Submitted That Met QC Criteria: November 25, 2025
• First Posted (Actual): December 8, 2025

Study Record Updates

• Last Update Posted (Actual): March 5, 2026
• Last Update Submitted That Met QC Criteria: March 3, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Pathological Conditions, Signs and Symptoms; Atrial Fibrillation; Investigative Techniques; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Techniques, Cardiovascular; Heart Function Tests; Electrodiagnosis; Magnetometry; Magnetocardiography
• Other Study ID Numbers: 25-008283

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