Repolarization abnormalities detected by magnetocardiography in patients with dilated cardiomyopathy and ventricular arrhythmias

Introduction: Abnormal repolarization is one of the acknowledged mechanisms leading to malignant ventricular arrhythmias, We used a novel magnetocardi ographic technique to investigate the role of inhomogeneous repolarization in patients with nonischemic dilated cardiomyopathy prone to sustained vent ricular arrhythmias. Methods and Results: Forty-nine dilated cardiomyopathy patients were studie d, 18 with a history of sustained ventricular tachycardia (n = 6) or ventri cular fibrillation (n = 12) and 31 with no ventricular arrhythmias, The mag netocardiogram was registered and QT apex and QT end intervals were determi ned by a computer algorithm, Inhomogeneity of repolarization was characteri zed with indices describing QT apex and QT end dispersion, and T wave end d uration. In addition, time-domain late fields of the QRS complex in magneto cardiography and QT dispersion in 12-lead ECG were determined. T wave end w as longer in the arrhythmia group in patients with sinus rhythm (87 +/- 15 msec vs 73 +/- 12 msec; P = 0.005) and in those not having bundle branch bl ock. Magnetocardiographic late fields of the QRS complex were not different between groups. QT apex and end dispersion on magnetocardiography or 12-le ad ECG showed no difference. Conclusion: Prolongation of the end part of the T wave revealed by magnetoc ardiography is related to malignant ventricular arrhythmias in dilated card iomyopathy, The results suggest that abnormal repolarization rather than de layed conduction underlies the arrhythmias in this disease.