Figure 1.
Construction of a QTc contour map from magnetocardiography (MCG).
Signals from 64-channel MCG traces before averaging, and the construction of repolarization map with a 21×21 resolution by signal-averaged vector-projected electrocardiogram (A). The spatial distribution of corrected QT (QTc) intervals was displayed on a QTc contour map (B).
Table 1.
Patient characteristics.
Table 2.
Magnetocardiography-derived parameters in patients with patients with thalassemia major and control subjects.
Figure 2.
Comparisons of mean QTc interval (A), SI-QTc (B), SD-QTc (C), and QTc dispersion (D) in patients and controls.
Patients were further divided into those with normal cardiac T2* value (≥20 ms) and those with abnormal cardiac T2* value (<20 ms). QTc = corrected QT interval; SI-QTc = smooth index of corrected QT intervals; SD-QTc = standard deviation of corrected QT intervals.
Figure 3.
Correlations between SI-QTc (A), SD-QTc (B), QTc dispersion (C) and loge cardiac T2* value.
QTc = corrected QT interval; SI-QTc = smooth index of corrected QT intervals; SD-QTc = standard deviation of corrected QT intervals.
Figure 4.
ROC curves of SI-QTc (A), SD-QTc (B), QTc dispersion (C), and cardiac T2* (D) for predicting the presence of adverse cardiac events.
The optimal cut-off value (labeled as the black dot on the ROC curve), sensitivity, and specificity of each individual parameter are shown. Data in the parenthesis indicate 95% confidence interval of the area under curve (AUC). QTc = corrected QT interval; SI-QTc = smooth index of corrected QT intervals; SD-QTc = standard deviation of corrected QT intervals.