[Late fields in magnetcardiography and late potentials in electrocardiography after acute myocardial infarction].
A high specificity and a high positive prediction has been reached in risk stratification for a sudden cardiac death after acute myocardial infarction (AMI) by combining multiple methods. But sensitivity and negative prediction are still not satisfying. There are the same physiological processes underlying magnetocardiography (MCG) and electrocardiography (ECG). Nevertheless, the signals in each method contain different information.


METHODS
We studied the cardiac magnetic fields in 50 patients after AMI and in 32 probands and calculated the magnetic late field (LF), according to Simsons late potential (LP) analysis. We defined normal values, according to the 95% confidence interval of the probands (QRS < =97 ms, RMS > = 0. 6, LAS < 25 ms).


RESULTS
We compared the results of LF and LP analysis regarding pathologic-nonpathologic and found 76% of the patients with the same results in both methods. Four patients had magnetic signals with low amplitude in the ST segment in contrast to the ECG result, while 6 patients with a "LP positive" diagnosis based on RMS and LAS only, did not show LF. In addition, we have found the magnetic QRS complex to be shorter than the electrical one.


CONCLUSIONS
In general, the results of LF measurement are similar to the ones of LP measurement. Presumably, there are intracardial currents, which are not detectable by ECG. Further studies are needed to evaluate the prognostic value in patients at high risk for cardiac arrhythmias.
Haas
J
J
Klinik für Innere Medizin III, Friedrich-Schiller-Universität, Erlanger Allee 101, D-07747 Jena, Germany.
Leder
U
U
Heinke
M
M
Nowak
H
H
Kühnert
H
H
Figulla
H R
HR
D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D016757:Death, Sudden, Cardiac / Q000209:etiology* / Q000517:prevention & control; D004562:Electrocardiography; D055590:Electromagnetic Phenomena; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D012016:Reference Values; D012680:Sensitivity and Specificity