Effectiveness of magnetocardiography to identify patients in need of coronary artery revascularization: a cross-sectional study

BACKGROUND

Patients with angina-like symptoms need invasive or non-invasive angiography to determine whether revascularization is necessary. For patients in need of revascularization, undergoing coronary computed tomography angiography (CCTA) may delay the treatment of revascularization and increase exposure to contrast agents and radiation. The aim of this cross-sectional study was to accessed the effectiveness of magnetocardiography (MCG) to identify patients who should undergo coronary revascularization.

METHODS

A total of 203 patients who were suffering from angina-like symptoms and underwent percutaneous coronary angiography (PCA) between July 27, 2015 and April 10, 2017 at the 8th Medical Center of Chinese PLA General Hospital, were enrolled in this cross-sectional study. In all patients, 12-lead electrocardiography (ECG) and MCG test were performed before PCA. For each subject. The value at every single sampling point was extracted from T wave of each MCG channel in time sequence. Pearson's correlation coefficients were calculated for each two T-waves. A binary logistic regression diagnosis model of these coefficients was established to identify patients in need of revascularization.

RESULTS

Ten pairings of coefficients were entered into diagnostic regression model as covariates. The area under the receiver operating characteristic (ROC) curve (AUC) was 0.747 (95% CI: 0.680-0.815), and the asymptotic P value was less than 0.001. At the cut-off value of 0.55, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.9%, 65.9%, 74.8%, 63.6% and 69.9%, and the positive and negative post-test probabilities were 65.9% and 25.7%. The accuracy, sensitivity, specificity, PPV and NPV for 12-lead ECG were 67.0%, 62.7%, 63.5%, 70.5% and 55.1%, respectively. However, when those acute myocardial infarction (AMI) patients were ruled out from both groups, the MCG model had an accuracy of 68.2%, a sensitivity of 70.1%, a specificity of 66.3%, a PPV of 68.5% and an NPV of 67.9%. But, the accuracy, sensitivity, specificity, PPV and NPV for 12-lead ECG were 60.0%, 55.2%, 65.1%, 62.3% and 58.1%, respectively.

CONCLUSIONS

Patients suffering from angina-like symptoms, with a logistic regression model value over 0.55, should be recommended for PCA.

Toward noninvasive monitoring of ongoing electrical activity of human uterus and fetal heart and brain

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Evaluated a fetal-maternal scanner for monitoring electrical maternal and fetal organ activity.

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The simulated scanner can monitor the uterine and fetal heart and brain activity online.

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Biomagnetic monitors similar to this instrument should be useful in clinical neurophysiology.

Objective

To evaluate whether a full-coverage fetal-maternal scanner can noninvasively monitor ongoing electrophysiological activity of maternal and fetal organs.

Methods

A simulation study was carried out for a scanner with an array of magnetic field sensors placed all around the torso from the chest to the hip within a horizontal magnetic shielding enclosure. The magnetic fields from internal organs and an external noise source were computed for a pregnant woman with a 35-week old fetus. Signal processing methods were used to reject the external and internal interferences, to visualize uterine activity, and to detect activity of fetal heart and brain.

Results

External interference was reduced by a factor of 1000, sufficient for detecting signals from internal organs when combined with passive and active shielding. The scanner rejects internal interferences better than partial-coverage arrays. It can be used to estimate currents around the uterus. It clearly detects spontaneous activity from the fetal heart and brain without averaging and weaker evoked brain activity at all fetal head positions after averaging.

Conclusion

The simulated device will be able to monitor the ongoing activity of the fetal and maternal organs.

Significance

This type of scanner may become a novel tool in fetal medicine.

Diagnostic outcomes of magnetocardiography in patients with coronary artery disease

OBJECTIVE

To evaluate the diagnostic outcomes of magnetocardiography (MCG) on the patients with coronary artery disease and compared the outcomes between MCG, ECG and Echocardiography.

METHODS

MCG measurements were performed on 101 patients with coronary artery disease and 116 healthy volunteers with a seven-channel magnetocardiographic system (MCG7, SQUID AG, Germany) installed in an unshielded room. CAD was diagnosed when stenosis ≥ 70% in ≥ 1 vessel. Three quantitative indicators were analyzed, R-max/T-max ratio, R value and á average angle.

RESULTS

R-max/T-max ratio of CAD group (6.30 ± 4.07) was much higher than that of healthy group (3.73 ± 1.41) (P < 0.001), R value of CAD group (69.16 ± 27.87)% was significantly higher than that of healthy group (34.96 ± 19.09)% (P < 0.001), á average angle of CAD group (221.46° ± 64.53°) was higher than that of healthy group (24.32° ± 20.70°) (P < 0.01). In 75 of 101 CAD patients (74.26%), MCG had abnormal mapping patterns. The resting ECG examination showed ischemic changes, such as abnormal Q waves and ST-T change in 49 patients (48.51%). Echocardiography revealed abnormal left ventricular wall motion and asynergy in 46 patients (45.54%). Thus, the diagnostic outcomes of MCG for the patients with CAD were much significant than those of ECG and echocardiography (P < 0.001).

CONCLUSIONS

Our result showed that resting MCG under condition of an advanced data analysis has higher diagnostic outcomes and is superior to ECG or echocardiography for patients with CAD. MCG can detect ST-segment displacement caused by ischemic myocardium, thus helpful in diagnosing coronary artery disease early.