Objective: To investigate the magnetocardiography (MCG) changes in coronary artery disease (CAD) patients with normal or unspecific changes in resting electrocardiogram (ECG).
Methods: MCG mapping was performed by MCG-7 (MaGIC, Magiscan GmbH) installed in an unshielded room. All patients underwent ECG and coronary angiogram examinations and patients with normal or unspecified ECG changes and coronary artery narrowing > or = 70% in at least 1-vessel were defined as CAD group (n = 120). Patients with normal coronary angiogram served as control (n = 82). Four parameters: ACTM (average classification of total maps), RAM (ratio of abnormal maps), CVEI (complex ventricular excitation index) and R-max/T-max ratio, were analyzed in CAD and control groups.
Results: RAM (62% vs. 35%) and ACTM (2.62 +/- 0.98 vs. 2.29 +/- 0.90, P < 0.05) were significantly higher in CAD group than in control group. CVEI was found in abnormal zone (-100 - 0) in CAD group while in normal zone (0 - 100) in control group. The ratio of Rmax/Tmax in CAD group was also significantly higher in CAD group than in control group (6.41 +/- 3.29 vs. 4.10 +/- 2.00, P < 0.01). ROC curve analysis indicates that RAM, CVEI and Rmax/Tmax ratio were helpful parameters for CAD diagnosis and the diagnostic sensitivity was 67.1%, 65.9% and 64.3%; the specificity was 65.1%, 68.3% and 68.3% respectively.
Conclusion: MCG was a useful tool for diagnosing chronic myocardium ischemia in CAD patients with normal or unspecific changes resting ECG.