Magnetocardiographic findings and follow-up in an asymptomatic Brugada patient. Effects of Flecainide and of exercise tests

The Brugada syndrome (BS) is a genetically transmitted arrhythmogenic disease, which requires risk stratification, especially in asymptomatic subjects. Recent studies have shown that magnetocardiographic mapping (MCG) at rest can detect abnormal current distribution located in the RVOT. Here we describe an asymptomatic 28 years old BS patient, studied with 12-lead ECG and 36-channel MCG for three times at rest, under effort and during flecainide (Flec) tests, along a four years follow-up. He had a type 2 BS ECG at rest, but normal physical examination, echocardiogram and MRI. Molecular screening of the SCNC5A open reading frame revealed a de novo missense mutation in the DII DIII linker, confirming the diagnosis of BS. For MCG assessment of ventricular repolarization (VR), magnetic field (MF) dynamics and MF gradient orientation, were computed during the ST interval and at the T wave peak. Current density reconstruction (CDR) and the strength of the equivalent current dipole (ECD) were calculated during the JT interval, to evidence potentially arrhythmogenic current flowing. In spite of Flec-induced ECG abnormality (typical type-1 ST elevation in V1 V3), MCG didn't show clear-cut variation of VR parameters, which didn't differ from those of healthy controls, at rest and under effort. After Flec, CDR, calculated every 10 ms from the J point, evidenced a change in the direction of the strongest current toward the right ventricular outflow tract, without a significant increase of the JT ECD strength. During the follow-up the patient was asymptomatic and no arrhythmia occurred. Further work is deserved to establish the predictive value of MCG for non-invasive risk stratification in asymptomatic BS patients with abnormal Flec test.