Magnetocardiographic mapping of QRS fragmentation in patients with a history of malignant tachyarrhythmias

Background: The identification of patients at increased risk for ventricula r tachycardia or ventricular fibrillation (VT/VF) and sudden cardiac death has consequences for therapeutic options and thus may reduce mortality in p atients with coronary artery disease (CAD). Hypothesis: We hypothesized that the intra-QRS fragmentation in magnetocard iographic recordings is increased in patients with CAD and with a history o f VT/VF. Methods: Multichannel magnetocardiography (MCG) was carried out in 34 healt hy controls, 42 patients with CAD without a history of VT/VF, and 43 patien ts with CAD and with a history of VT/VF. The intra-QRS fragmentation was qu antified by anew fragmentation score. Its spatial distribution was investig ated using two-dimensional (2-D) contour maps according to the sensor posit ion of the 49-channel magnetogradiometer. Results: Patients with CAD and with a history of VT/VF had significantly in creased QRS fragmentation compared with patients with CAD without VT/VF or controls (72.9 +/- 37.5, 48.5 +/- 14.3, and 42.5 +/-7.8, respectively; p<0. 05). The area of high fragmentation in 2-D contour maps was twice as large in patients with than in those without a history of VT/VF (represented by t he number of MCG channels with high fragmentation: 26.3<plus/minus>15.5 vs. 12.4 +/-9.9, p<0.0001). Patients prone to VT/VF could be identified with a sensitivity of 64% and a specificity of 90%. Conclusion: In patients with CAD and with a history of VT/VF, intra-QRS fra gmentation is increased and the area of high fragmentation in 2-D contour m aps is enlarged. These findings may be helpful in identifying patients with CAD at risk for malignant tachyarrhythmias.