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- Title
Value of Magnetocardiographic QRST Integral Maps in the Identification of Patients at Risk of Ventricular Arrhythmias.
- Authors
Hren, Rok; Steinhoff, Uwe; Gessner, Christof; Endt, Peter; Goedde, Peter; Agrawal, Rahul; Oeff, Michael; Lux, Robert L.; Trahms, Lutz
- Abstract
It has been shown that regional ventricular repolarization properties can be reflected in body surface distributions of electrocardiographic QRST deflection areas (integrals). We hypothesize that these properties can be reflected also in the magnetocardiographic QRST areas and that this may be useful for predicting vulnerability to ventricular tachyarrhythmias. Magnetic field maps were obtained during sinus rhythm from 49 leads above the anterior chest in 22 healthy (asymptomatic) control subjects (group A) and in 29 patients with ventricular arrythmias (group B). In each subject, the QRST deflection area was calculated for each lead and displayed as an integral map. The mean value of maximum was significantly larger in the control group A than in the patient group B (1,626 ± 694 pTms vs 582 ± 547 pTms, P < 0.0001). To quantitatively assess intragroup variability in the control group A and intergroup variability of the control and patient groups, we used the correlation coefficient r and covariance CT. These indices showed significantly less intragroup than intergroup variation (e.g., in terms of σ, 28.0 ⋅ 10-6 ± 12.3 ⋅ 10-6 vs 3.4 ⋅ 10-6 ± 12.5 ⋅ 10-6, P < 0.0001). Each QRST integral map was also represented as a weighted sum of 24 basis functions (eigenvectors) by means of Karbunen-Loeve transformation to calculate the contribution of the nondipolar eigenvectors (all eigenvectors beyond the third). This percentage nondipolar content of magnetocardiographic QRST integral maps was significantly higher in the patient group B than in the control group A (13.0% ± 9.1 % vs 2.6% ± 2.0%, P < 0.0001). Discriminations between control subjects and patients with ventricular arrhythmias based on magnitude of the maximum, covariance a: and nondipolar content were 90.2%, 90.2%, and 86.3% accurate, with a sensitivity of 89.7%. 93.1%. and 75.9%, and...
- Subjects
ELECTROCARDIOGRAPHY; VENTRICULAR tachycardia; TACHYARRHYTHMIAS; MAGNETIC fields; PATIENTS; EIGENVECTORS; ARRHYTHMIA
- Publication
Pacing & Clinical Electrophysiology, 1999, Vol 22, Issue 9, p1292
- ISSN
0147-8389
- Publication type
Article
- DOI
10.1111/j.1540-8159.1999.tb00622.x