Magnetocardiography did not uncover electrically silent ischemia in an in-silico study case

Abstract

Over the last decades, the information content derived from cardiac electric and magnetic field measurements has been debated. Our co-workers Wilhelms et al. investigated electrically silent acute ischemia in human ventricles caused by occlusion of a coronary artery. In the present work, we extend the previous study by calculating associated magnetic fields produced by early stage acute ischemia with varying transmural extent. Multiscale computational simulations were performed for calculations of body surface potential maps (BSPM) and magnetocardiograms (MCG) on a magnetometer sensor matrix situated above the anterior chest wall. Depending on the ischemia size, the ST-segments of the simulated electrocardiograms (ECG) experienced depression for subendocardial cases and elevation for transmural ischemia. One intermediate extent resulted in a zero ST-segment which makes it diagnostically indistinguishable from the healthy case. Magnetic field calculations for this electrically silent ischemia also revealed no difference compared to the control case. Otherwise, both ECG and MCG signals during ST-segments showed either depression or elevation from zero line. In this simulation study, MCG did not deliver additional information to uncover electrically silent ischemia. For a general conclusion, further in-silico investigations with different ischemia shapes, sizes and positions should be performed and clinical studies with recordings of both ECG and MCG signals have to be conducted.