Repolarization abnormalities detected by magnetocardiography in patients with dilated cardiomyopathy and ventricular arrhythmias.
BACKGROUND
Abnormal repolarization is one of the acknowledged mechanisms leading to malignant ventricular arrhythmias. We used a novel magnetocardiographic technique to investigate the role of inhomogeneous repolarization in patients with nonischemic dilated cardiomyopathy prone to sustained ventricular arrhythmias.


RESULTS
Forty-nine dilated cardiomyopathy patients were studied, 18 with a history of sustained ventricular tachycardia (n = 6) or ventricular fibrillation (n = 12) and 31 with no ventricular arrhythmias. The magnetocardiogram was registered and QT apex and QT end intervals were determined by a computer algorithm. Inhomogeneity of repolarization was characterized with indices describing QT apex and QT end dispersion, and T wave end duration. In addition, time-domain late fields of the QRS complex in magnetocardiography and QT dispersion in 12-lead ECG were determined. T wave end was 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 block. Magnetocardiographic late fields of the QRS complex were not different between groups. QT apex and end dispersion on magnetocardiography or 12-lead ECG showed no difference.


CONCLUSIONS
Prolongation of the end part of the T wave revealed by magnetocardiography is related to malignant ventricular arrhythmias in dilated cardiomyopathy. The results suggest that abnormal repolarization rather than delayed conduction underlies the arrhythmias in this disease.
Korhonen
P
P
Division of Cardiology, Helsinki University Central Hospital, Finland. petkor@clarinet.fi
Väänänen
H
H
Mäkijärvi
M
M
Katila
T
T
Toivonen
L
L
D000328:Adult; D002309:Cardiology / Q000379:methods*; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000503:physiopathology*; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology*; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology*