Predictive value of rest magnetocardiography in patients with stable angina

Abstract

Abstract. Magnetocardiographic mapping (MCG) is increasingly used for non-invasive early detection of ischemia in patients with acute chest pain. This study was aimed to evaluate the predictive value of MCG, for the diagnosis of ischemia in patients with coronary artery disease (CAD) and stable angina (StA). 51 pts (age 63 ± 10.7 years) with CAD (all chest pain free at the time of MCG) and 52 healthy volunteers were studied at rest with an unshielded 36-channel MCG system (sensitivity: 20 fT/√Hz, above 1 Hz). 42 pts underwent coronary angiography (CAng) (21 after MCG scan). 39 pts had stress SPECT; 32 had both CAng and SPECT. Analysis of ventricular repolarization (VR) was performed utilizing different methods for interactive and automated analysis of T-wave dynamics and of the effective magnetic vector (EMV) parameters. For all pts, best sensitivity, specificity, PPV, NPV and predictive accuracy of the MCG for the detection of ischemia were 56%, 96%, 94%, 69% and 78%, respectively (with EMV). If pts with previous myocardial infarction (MI) were excluded, best sensitivity, specificity, PPV, NPV and predictive accuracy of the MCG for the detection of ischemia were 83%, 96%, 94%, 89% and 91%, respectively (detected with EMV). Comparative values calculated from ECG were 38%, 100%, 100%, 80% and 82%, respectively. As compared with previous results in pts with ACS, the T-wave analysis seems to be less sensitive in pts with chronic CAD and previous MI. Further work is needed to better define MCG parameters to be used for the diagnosis of myocardial ischemia in pts with CAD and to differentiate VR abnormalities due to coexistent ventricular hypertrophy, previous MI, or other cardiomyopathy.