Changes in dipolar structure of cardiac magnetic field maps after ST elevation myocardial infarction.
BACKGROUND
Pathological changes in cardiac electrophysiology have been investigated in coronary artery disease using magnetocardiography. Aim of this work was to examine the structure of cardiac magnetic field maps (MFM) during ventricular depolarization and repolarization in patients with acute ST elevation myocardial infarction (STEMI).


METHODS
Magnetocardiograms were recorded in 39 healthy subjects and 97 patients who had been successfully revascularized after STEMI. Using the Karhunen-Loeve transform, 12 eigenmaps were constructed for six intervals within the QT interval of each subject's signal-averaged data. The relative information content of the eigenmaps was compared between STEMI patients and healthy subjects.


RESULTS
Relative nondipolar content was between 0.03% and 0.52% higher in the STEMI group, (P < 0.001 for the repolarization intervals). Information content of the first dipolar eigenmap in the STEMI group was reduced by 2.6%-11.7% (P < 0.001 for the repolarization intervals). STT interval was best able to discriminate between groups: area-under-the-curve for nondipolar content was 85.8% (P < 0.001), for the first eigenmap 91.7% (P < 0.001). Severity of infarction was reflected in lower STT interval map 1 content for patients with anterior versus posterior infarction (83%± 11% vs. 87%± 10%, P < 0.05), with wall motion disturbances (84%± 11% vs. 92%± 7%, P < 0.001) and with microvascular obstruction (81%± 12% vs. 87%± 10%, P < 0.05). Regression analysis showed that patients with lower ejection fraction tended to have less information content (P < 0.001).


CONCLUSIONS
STEMI is associated with a loss of spatial coherence during repolarization, as quantified by principal component analysis of cardiac MFM.
Department of Biomagnetism, Grönemeyer Institute for Microtherapy, University Witten/Herdecke, Universitätsstrasse 142, Bochum, Germany. petervl@microtherapy.de
Peter
P
Van Leeuwen
Birgit
B
Hailer
Alexander
A
Beck
Gregor
G
Eiling
Dietrich
D
Grönemeyer
D000328:Adult; D019540:Area Under Curve; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D019028:Magnetic Resonance Imaging, Cine; D053798:Magnetocardiography; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D025341:Principal Component Analysis; D012372:ROC Curve