Detection of coronary artery disease with MCG.

Abstract

The diagnosis of cardiac ischemia related to coronary artery disease (CAD) is a clinical challenge. Despite many methods clinically available, the predictive value of each is still limited. Magnetocardiography (MCG) offers new insights in the electrogenesis of the disease. In the last decade a number of studies using biomagnetometers have dealt with the identification of CAD patients using coronary angiography as a gold standard. As the availability of these systems is limited, studies have focused either on exercise-induced ischemia or on chronic ischemia and the infarct scar at rest. Different parameters have been developed based on signal morphology, time intervals, source parameters or magnetic field map analysis. Concerning signal morphology, main work concentrates on ST-depression, ST-T signal amplitude as well as QRS and ST-T integrals. Dealing with time intervals, most studies focus on the QT interval. The evaluation of of QT dispersion spatially in the MCG, reflecting regional heterogeneity of repolarization, improved the identification of CAD patients. Besides the calculation of the equivalent current dipole during de- and repolarization, parameters of the magnetic field orientation were used to identify CAD patients and localize exercise-induced ischemic regions. Heart rate adjusted alteration in the magnetic field orientation allowed the quantification of ischemia-induced changes in MCG. The estimation of current density (CDV) further enabled to separate healthy subjects from CAD patients at rest. In the course of interventional therapy CDV maps returned toward that of healthy subjects.Thus, there is justification for routine clinical use of the MCG in the diagnosis of CAD.