Magnetocardiographic Study of Ventricular Repolarization in Rett Syndrome

Rett syndrome (RS) is a genetic disorder predominant in females, with sudden death (SD), thought to be due ventricular repolarization alterations (VRa) and/or of ANS dysfunction. So far for risk-assessment, heart rate variability (HRV), QT duration and its dispersion (QTd) were measured with ECG. However SD has occurred in RS without VRa at ECG. Our aim was to study VRa in RS patients (pts), with magnetocardiography (MCG). Methods: 9 female (age:1-34 years) RS pts (stage II-IV) were studied with an unshielded 36-channels MCG system (sensitivity: 20 fT/Hz½,). To assess VRa with MCG, QTpeak, QTend, Tpeak-Tend intervals and QTd, corrected for heart rate (HR), were measured. Moreover ST integral and Tpeak magnetic field (MF) orientation (α angle), ST dynamics and ST stability were also calculated. 10 age-matched (4-33 years) normal controls (NC) were studied for comparison. HRV time- (TD) and frequency- (FD) domain parameters were evaluated from 24 hours 12-lead Holter ECG. Results: In RS pts, HR-corrected QTend was longer: 427±16 (RS) vs 412±14 (NC) ms (pConclusions: In RS, MCG parameters evidenced VRa in stage IV pts, although both QTend and QTd were still within normal limits. Further work on a larger population and a prolonged follow-up are needed to define the predictive value of MCG VRa in RS