Usefulness of Magnetocardiography to Detect Coronary Artery Disease and Cardiac Allograft Vasculopathy

BACKGROUND: Electrophysiological information as well as anatomic information are important for the detection of coronary artery lesions. The aim of this study was to assess the efficacy of resting magnetocardiography (MCG) in stable coronary artery disease (CAD) and cardiac allograft vasculopathy (CAV). METHODS AND RESULTS: MCG and coronary angiography were performed within 1 month in 75 patients with suspected CAD and in 26 subjects after orthotopic heart transplantation (OHT). Plaque volumes were additionally measured on intravascular ultrasound in OHT recipients. The spatially distributed QT(c) interval maps were constructed with 64-channel MCG. A T-wave propagation map and QT(c) heterogeneity index including QT(c) dispersion and smoothness index of QT(c) (SI-QT(c)) were derived for ischemia detection and localization. CAD patients had higher QT(c) dispersion and SI-QT(c). Receiver operating characteristic curve analysis identified SI-QT(c) ≥9 ms, QT(c) dispersion ≥79 ms as the optimal cut-off for detecting CAD (diagnostic accuracy, 0.7953, 0.7819), better than T-wave propagation (0.6594, P<0.05). There was no significant difference of QT(c) dispersion between CAD and OHT subjects. In OHT recipients, QT(c) dispersion positively correlated with plaque volume, and SI-QT(c) progressively increased after transplantation. Using T-wave propagation mapping, regionally increased dispersion could be demonstrated in CAD patients, but increased dispersion was noted in fewer OHT recipients. CONCLUSIONS: MCG is clinically feasible as a non-invasive tool for diagnosis of CAD, and could be used as a surrogate marker of CAV.