M. Oeff

Magnetocardiographic analysis of the two-dimensional distribution of intra-QRS fractionated activation

The spatial distribution of high-frequency components in magnetic signals during the QRS complex of the human heartbeat was investigated. Cardiomagnetic signals were recorded simultaneously using 49 first-order magnetogradiometer channels of a multi-SQUID system with a low noise power density. The QRS fragmentation score S, as a measure of the fragmentation of the bandpass-filtered QRS complex, was examined for its sensitivity and specificity to discriminate 34 healthy volunteers, 42 post-myocardial infarction patients and 43 patients with coronary heart disease and with a history of malignant sustained ventricular tachycardia or ventricular fibrillation. The multichannel information was visualized by two-dimensional mapping of the score values of the single channels. By averaging the score values for the seven central channels, S7, the score values of all 49 channels, S49, and calculating the standard deviation for all 49 channels, D49, a higher sensitivity and specificity for detecting patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) was reached than by analysis of a single channel. Combination of these parameters furnishes a sensitivity of 90% and a specificity of 70% for identifying patients prone to VT/VF. The results were compared with diagnostic information obtained from the QRS duration of the signal as well as with results obtained by modified QRS integral mapping.

Magnetocardiographic Localization of the Origin of Ventricular Ectopic Beats

Magnetocardiogruphic mapping opens new perspectives for three‐dimensional localization of cardiac electrical activation. Using a 37‐channel SQUID magnetometer equipment with high shielding, the origin of abnormal ventricular aclivalion was investigated in 18 patients ivith Wolff‐Parkinson‐White syndrome prior to catheter ablation and in 5 of 31 patients with coronary artery disease having a sufficient number of monomorphic ventricular extrasystoies to enable evaluation. In ali WPW‐patients, the site of the earliest dello‐wave activation was projected onto the AV‐valve plane in accordance with the MR images. The result of magnetocardiographic localization was then compared to the site of successful catheter oblation delermined by digital imaging processing. After optimization of the algorithms, both sites were in the various planes at the foliowing distance from each other; X‐plane; 0.8 ± 0.9 cm, Y‐pIane; 1.1 ± 1.0 cm and Z‐piane; 1.5 ± 1.0 cm. In three‐dimensional projection, the mean difference in space between both positions was calculated to be 2.1 ± 1.7 cm. After this vahdofion ventricular premature beats were localized in another group of patients. In 4 of 5 palienfs their origin was found at the border of infarct areas. In each case, the progression of the ventricular activation couid be pursued. The detected structure of the magnetic field distribution of the VBPs exhibited a stable bipolar patlern, which is comparable to that of venlricuiar tachycardia, and its algorithms may be used to localize the origin of ventricular lachycardia. Thus, non‐invasive magnetocardiographic mapping localizes abnormal ventricuiar activations with fair accuracy, which makes it an useful adjunct for invasive investigations as well as studies of the pathophysiology of arrhythmias.

Fragmentation of bandpass-filtered QRS-complex of patients prone to malignant arrhythmia.

The structure of high-frequency components of electric and magnetic signals from the heart during the depolarisation phase is investigated. After averaging and broadband filtering with a binomial bandpass filter (37 Hz-90 Hz), the fragmentation of the QRS-complex is quantified. The number of extrema M and a new score value S are calculated from the signals of three electrical leads and one magnetic lead of 23 healthy subjects, 23 patients with coronary heart disease (CHD) without reported event of ventricular tachycardia or fibrillation at the time of measurement, and eight patients with CHD who have suffered from malignant tachycardia. For the parameter M, the sensitivity and specificity for healthy subjects against patients with CHD and ventricular tachycardia for the magnetic lead (the best electric lead) are 100% (75%) and 100% (100%). For the magnetic lead (best electric lead) and parameter S, the sensitivity and specificity are 100% (75%) and 95.6% (100%).

Value of magnetocardiographic QRST integral maps in the identification of patients at risk of ventricular arrhythmias.

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 arrhythmias (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 σ. 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 Karhunen‐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 σ, and nondipolar content were 90.2%, 90.2%, and 86.3% accurate, with a sensitivity of 89.7%, 93.1%, and 75.9%, and a specificity of 90.9%, 86.4%, and 100%. We have shown that magnitude of the maximum and indices of variability and nondipolarity of the magnetocardiographic QRST integral maps may predict arrhythmia vulnerability. This finding is in agreement with earlier studies that used body surface potential mapping and suggests that magnetic field mapping may also be a useful diagnostic tool for risk analysis.

Transcatheter laser photocoagulation for treatment of cardiac arrhythmias

Cardiac arrhythmias can be treated by endocardial laser photocoagulation of arrhythmogenic foci. Transcatheter continuous wave Nd-YAG laser (1064 nm) photocoagulation was studied for impairment of atrioventricular (AV) conduction. First, studies on the dose-effect relation revealed that in vitro applications to ventricular endocardium produce dose-dependent coagulation necrosis. However, energy absorption varies in tissue specimens from different experimental animals and humans and may be dependent on differences in surfaces ultrastructure. Ten times more energy is required for human endocardial specimens than for canine endocardium.The long-term in vivo experiment demonstrates that the chronic laser-induced myocardial lesion size is proportional to the applied energy, exhibit no arrhythmogenic effects and may thus be suitable for the treatment of cardiac arrhythmias. Transcatheter laser application using a combined electrode-laser catheter reliably achieved a slowing of atrioventricular AV conduction (AV modification) or a complete AV block.Thus, the transcatheter application of Nd-YAG laser energy at the AV node may be useful for treatment of tachyarrhythmias in man.

Magnetkardiographischer Nachweis abnormer intraventrikulärer Erregungsausbreitung bei ischämie-bedingter Herzerkrankung ohne und mit Tachykardien

UNLABELLED Fragmented and delayed activation of ventricular myocardium can cause malignant tachyarrhythmias. By detection of ventricular late potentials only a severely delayed depolarisation is registered, but not the intra QRS-activation. The aim of this study was to examine the complete phase of ventricular depolarisation, to detect and to quantify abnormal electrical activation by magnetocardiography and to estimate in a small group of patients with coronary heart disease the prognostic significance.In 26 healthy subjects, 32 patients after myocardial infarction without malignant ventricular arrhythmias and 10 patients with coronary heart disease and a history of sustained, monomorph ventricular tachycardia magnetocardiography was performed in a magnetically shielded room. To quantify the fragmentation of QRS a fragmentation-index (FI) was calculated. Besides signal averaged ECG, in patients with coronary heart disease cardiac catheterisation and in patients with arrhythmias electrophysiological testing was performed. The FI for the three groups was significantly different (p<0,005). The mean FI in the group of healthy subjects was 20,4+/-5,4, in the group of postinfarction-patients without arrhythmias 27+/-12,1 and in the group of patients with coronary heart disease and ventricular arrhythmias 49,5+/-17,9. Dichotomized at 36 the sensitivity was 80%, the specifity 93%, the positive predictive value was 66% and the negative predictive value 96%. The FI was correlated to the extent of regional wall-motion-irregularity and global ejection fraction.Analyzing late potentials, the values for sensitivity and positive predictive value were surprisingly low (20% and 50%, respectively). The specifity was 96%, the negative predictive value was 88%. Calculating the FI on the basis of electrical signals only an insufficient discrimination of the groups was possible.In the follow-up period of two years one post-infarctional patient was resusciated because of ventricular fibrillation. The FI of this patient was 17.One patient with coronary 3-vessel-disease and left ventricular ejection fraction of 50% died due to acute myocardial infarction, his FI was 39. CONCLUSION By means of magnetocardiography fragmented ventricular activation in patients with coronary heart disease was demonstrated even within the QRS-complex and could be correlated to ventricular tachyarrhythmias.ZusammenfassungFragmentierte und verzögerte Aktivierung des ventrikulären Myokards kann die Ursache für maligne tachykarde Herzrhythmusstörungen sein. Durch den Nachweis ventrikulärer Spätpotentiale wird nur eine sehr stark verzögerte Depolarisation, nicht aber die Intra-QRS-Aktivierung erfaßt. Ziel dieser Untersuchung war es daher, die gesamte Phase der ventrikulären Depolarisation zu untersuchen, eine abnorme elektrische Aktivierung magnetokardiographisch zu erfassen und zu quantifizieren sowie an einem kleinen Kollektiv koronarkranker Patienten die prognostische Bedeutung abzuschätzen.Bei 26 Gesunden, 32 Patienten nach akutem Myokardinfarkt ohne maligne ventrikuläre Arrhythmien und 10 Patienten mit koronarer Herzkrankheit und anhaltender, monomorpher ventrikulärer Tachykardie in der Anamnese wurde in einem magnetisch abgeschirmten Raum eine Magnetokardiographie mittels Superconducting Quantum Interference Device (SQUID)-Elementen durchgeführt. Zur Quantifizierung der fragmentierten Aktivierung im QRS wurde ein Fragmentations-Index (FI) berechnet. Bei jedem Patienten bzw. Gesunden wurde außerdem ein hochverstärktes EKG zur Analyse von Spätpotentialen, bei den Patienten mit koronarer Herzkrankheit eine Herzkatheteruntersuchung und bei den Patienten mit ventrikulären Herzrhythmusstörungen eine elektrophysiologische Untersuchung durchgeführt.Es ergaben sich für die drei Gruppen hochsignifikant unterschiedliche Werte für den FI (p<0,005). Der mittlere FI in der Gruppe der Gesunden betrug 20,4±5,4, in der Gruppe der Postinfarkt-Patienten ohne Arrhythmien 27,2±12,1 und in der Gruppe der Patienten mit koronarer Herzkrankheit und ventrikulären Tachykardien 49,5±17,9. Bei einem Schwellenwert von 36 ergab sich eine Sensitivität von 80%, eine Spezifität von 93%, ein positiv prädiktiver Wert von 66% und ein negativ prädiktiver Wert von 96% bezüglich des Auftretens einer anhaltenden ventrikulären Tachykardie. Der Fragmentations-Index war korreliert mit dem Ausmaß der regionalen Wandbewegungsstörungen und der globalen linksventrikulären Ejektionsfraktion.Bei der Spätpotentialanalyse ergaben sich überraschend niedrige Werte für Sensitivität (20%) und positiv prädiktiven Wert (50%) bei einer Spezifität von 96% und einem negativ prädiktiven Wert von 88%. Bei der Errechnung des FI aus den elektrischen Signalen konnten die drei Gruppen nur unzureichend unterschieden werden.In der 2-jährigen Nachverfolgungsperiode der Postinfarkt-Patienten erlitt ein Patient Kammerflimmern und konnte erfolgreich reanimiert werden. Der FI dieses Patienten betrug 17.Ein Patient mit koronarer 3-Gefäß-Erkrankung verstarb an einem akuten Myokardinfarkt. Sein FI betrug 39.Schlußfolgerung: Mittels der Magnetokardiographie konnte eine fragmentierte ventrikuläre Aktivierung bei Patienten mit koronarer Herzkrankheit auch im QRS-Komplex nachgewiesen werden und zu abgelaufenen ventrikulären Tachykardien korreliert werden.SummaryFragmented and delayed activation of ventricular myocardium can cause malignant tachyarrhythmias. By detection of ventricular late potentials only a severely delayed depolarisation is registered, but not the intra QRS-activation. The aim of this study was to examine the complete phase of ventricular depolarisation, to detect and to quantify abnormal electrical activation by magnetocardiography and to estimate in a small group of patients with coronary heart disease the prognostic significance.In 26 healthy subjects, 32 patients after myocardial infarction without malignant ventricular arrhythmias and 10 patients with coronary heart disease and a history of sustained, monomorph ventricular tachycardia magnetocardiography was performed in a magnetically shielded room. To quantify the fragmentation of QRS a fragmentation-index (FI) was calculated. Besides signal averaged ECG, in patients with coronary heart disease cardiac catheterisation and in patients with arrhythmias electrophysiological testing was performed. The FI for the three groups was significantly different (p<0,005). The mean FI in the group of healthy subjects was 20,4±5,4, in the group of postinfarction-patients without arrhythmias 27±12,1 and in the group of patients with coronary heart disease and ventricular arrhythmias 49,5±17,9. Dichotomized at 36 the sensitivity was 80%, the specifity 93%, the positive predictive value was 66% and the negative predictive value 96%. The FI was correlated to the extent of regional wall-motion-irregularity and global ejection fraction.Analyzing late potentials, the values for sensitivity and positive predictive value were surprisingly low (20% and 50%, respectively). The specifity was 96%, the negative predictive value was 88%. Calculating the FI on the basis of electrical signals only an insufficient discrimination of the groups was possible.In the follow-up period of two years one post-infarctional patient was resusciated because of ventricular fibrillation. The FI of this patient was 17.One patient with coronary 3-vessel-disease and left ventricular ejection fraction of 50% died due to acute myocardial infarction, his FI was 39.Conclusion: By means of magnetocardiography fragmented ventricular activation in patients with coronary heart disease was demonstrated even within the QRS-complex and could be correlated to ventricular tachyarrhythmias.

Zeitreihen-Analyse von Herzsignalen zur Detektion abnormer Myokard-Aktivierung

The variability of electric and magnetic signals from the heart during the depolarization phase is investigated. A signal processing method is developed which provides estimates for the beat-to-beat variability of the QRS-complex. The method is based on the decomposition of the depolarization signal into bandpass signals by means of the Morlet wavelet transform. The beat variability of the depolarization signal is estimated by normalized variances of the envelope and instantaneous frequency of bandpass signals. Time intervals of the bandpass filtered depolarization signals having a high signal-to-noise ratio are selected by applying an analysis based on phase statistics. The method was tested by experimental data taken from ECG and MCG measurements of healthy persons and patients prone to malignant ventricular tachycardia (VT) or ventricular fibrillation (VF). Results suggest that the calculated variance parameters permit the characterization of beat variable depolarization signals and distinguish VT/VF patients from healthy persons. The method developed can be used to obtain additional information concerning abnormal heart signals which is attenuated when applying signal averaging.Summary The variability of electric and magnetic signals from the heart during the depolarization phase is investigated. A signal processing method is developed which provides estimates for the beat-to-beat variability of the QRS-complex. The method is based on the decomposition of the depolarization signal into bandpass signals by means of the Morlet wavelet transform. The beat variability of the depolarization signal is estimated by normalized variances of the envelope and instantaneous frequency of bandpass signals. Time intervals of the bandpass filtered depolarization signals having a high signal-to-noise ratio are selected by applying an analysis based on phase statistics. The method was tested by experimental data taken from ECG and MCG measurements of healthy persons and patients prone to malignant ventricular tachycardia (VT) or ventricular fibrillation (VF). Results suggest that the calculated variance parameters permit the characterization of beat variable depolarization signals and distinguish VT/VF patients from healthy persons. The method developed can be used to obtain additional information concerning abnormal heart signals which is attenuated when applying signal averaging.Zusammenfassung Die Variabilität des Herzsignals während der Depolarisationsphase wird untersucht. Die entwickelte Signalverarbeitungsmethode liefert Kennwerte zur Bestimmung der Schlag-zu-Schlag-Variabilität des Depolarisationssignals. Die Methode basiert auf der Dekomposition des Depolarisationssignals in Bandpasssignale mittels der Morlet-Wavelet-Transformation. Die Schlagvariabilität wird durch die normalisierten Varianzen von Einhüllender und Momentanfrequenz der Bandpasssignale bewertet. Ausgewertet werden Signalbereiche mit großem Signal-/Rauschleistungsverhältnis. Die erforderliche Selektion leistet ein Signalverarbeitungsalgorithmus, der die Phasenvarianz von Bandpasssignalen berechnet. Mit der Methode wurden Elektrokardiogramme und Magnetokardiogramme von Infarktpatienten analysiert. Die Resultate weisen signifikante Unterschiede zwischen der Patienten- und Kontrollgruppe aus. Die entwickelte Methode zur Einzelschlaganalyse von Herzsignalen liefert zusätzliche Information zu abnormalen Herzpotentialen, die durch Auswerteverfahren, die auf einer Signalmittelung basieren, unterdrückt wird.

Einzelschlagregistrierung verspäteter ventrikulärer Depolarisationen und ihre Frequenzanalyse mit der Fast-Fourier-Transformation. Methodische Aspekte

Verspatete ventrikulare Depolarisationen im hochauflosenden EKG werden durch die visuelle oder automatische (11, 17) Beurteilung der zeitlichen Anderung ihrer Spannungsamplitude ermittelt. In neuerer Zeit wurde von Vorteilen der Frequenzanalyse verspateter Depolarisationen mit der Fast-Fourier-Transformation (FFT) berichtet (2, 3).

Magnetokardiographisches Mapping: QT Dispersion bei Patienten mit koronarer Herzkrankheit mit und ohne ventrikuläre Tachykardien

Eine Dispersion der QT-Zeit, die im Oberfl~ichen EKG gemessen wird, wurde sowohl fa Gesunde als auch fa verschiedene Erkrankungen beschrieben. Eine erh6hte QT Dispersion fiel z.B. bei Patienten mit koronarer Herzkrankheit, Patienten mit Dilatativer Kardiomyopathie, Hypertropher Kardiomyopathie und bei Patienten mit Long QT-Syndrom auf (t, 2, 3, 4, 5). Experimentell konnte an Langendorff-perfundierten Kaninchenherzen eine Ubereinstimmung der QT Dispersion epikardialer monophasischer Aktionspotentiale mit Elektrogrammen ira Oberfl~chen-EKG gezeigt werden (6). Demzufolge scheint die QT Dispersion im Oberfl/ichen-EKG ein Korrelat der lokal inhomogenen Repolarisation bei bestimmten Patienten zu sein. So wie ein Zusammenhang zwischen expe¡ nachgewiesener Inhomogenit/~t der Repola¡ und erh6hter ventrikul~rer Vulnerabilit~it besteht (6, 7, 8), konnte in klinischen Studien eine erh6hte QT Dispersion ira Oberfl~ichenEKG als Risikofaktor fa ventrikul/ire Arrhythmien ausgemacht werden (9). Allerdings ist die Bestimmung der QT Dispersion problematisch (10). Es ergeben sich vor allem bei der Festlegung des T-Wellen Endes Schwierigkeiten, wenn die T-Welle flach oder biphasisch ist oder wenn sich eine U-Welle anschliel3t. Die Magnetokardiographie ist ein relativ neues Verfahren, mit dem das voto Herzen ausgehende magnetische Feld bera bestimmt wird. Mit einem Mehr-Kanal-System l~iBt sich ohne viel Aufwand ein pr5kordiales Mapping mit im Vergleich zum 12-Kanal EKG hoher r~iumlicher Aufl6sung durchfa Ziel di• Studie war es, di• Wertigkeit der QT Dispersion nach magnetokardiographischen Multi-Kanal-Mapping an Patienten mit koronarer Herzkrankheit mit und ohne ventrikul~ire Tachykardien sowie an einem Kontrollkollektiv zu a252

Magnetcardiographic detection of abnormal intraventricular activation in patients with ischemic heart disease with and without tachycardia

UNLABELLED Fragmented and delayed activation of ventricular myocardium can cause malignant tachyarrhythmias. By detection of ventricular late potentials only a severely delayed depolarisation is registered, but not the intra QRS-activation. The aim of this study was to examine the complete phase of ventricular depolarisation, to detect and to quantify abnormal electrical activation by magnetocardiography and to estimate in a small group of patients with coronary heart disease the prognostic significance.In 26 healthy subjects, 32 patients after myocardial infarction without malignant ventricular arrhythmias and 10 patients with coronary heart disease and a history of sustained, monomorph ventricular tachycardia magnetocardiography was performed in a magnetically shielded room. To quantify the fragmentation of QRS a fragmentation-index (FI) was calculated. Besides signal averaged ECG, in patients with coronary heart disease cardiac catheterisation and in patients with arrhythmias electrophysiological testing was performed. The FI for the three groups was significantly different (p<0,005). The mean FI in the group of healthy subjects was 20,4+/-5,4, in the group of postinfarction-patients without arrhythmias 27+/-12,1 and in the group of patients with coronary heart disease and ventricular arrhythmias 49,5+/-17,9. Dichotomized at 36 the sensitivity was 80%, the specifity 93%, the positive predictive value was 66% and the negative predictive value 96%. The FI was correlated to the extent of regional wall-motion-irregularity and global ejection fraction.Analyzing late potentials, the values for sensitivity and positive predictive value were surprisingly low (20% and 50%, respectively). The specifity was 96%, the negative predictive value was 88%. Calculating the FI on the basis of electrical signals only an insufficient discrimination of the groups was possible.In the follow-up period of two years one post-infarctional patient was resusciated because of ventricular fibrillation. The FI of this patient was 17.One patient with coronary 3-vessel-disease and left ventricular ejection fraction of 50% died due to acute myocardial infarction, his FI was 39. CONCLUSION By means of magnetocardiography fragmented ventricular activation in patients with coronary heart disease was demonstrated even within the QRS-complex and could be correlated to ventricular tachyarrhythmias.ZusammenfassungFragmentierte und verzögerte Aktivierung des ventrikulären Myokards kann die Ursache für maligne tachykarde Herzrhythmusstörungen sein. Durch den Nachweis ventrikulärer Spätpotentiale wird nur eine sehr stark verzögerte Depolarisation, nicht aber die Intra-QRS-Aktivierung erfaßt. Ziel dieser Untersuchung war es daher, die gesamte Phase der ventrikulären Depolarisation zu untersuchen, eine abnorme elektrische Aktivierung magnetokardiographisch zu erfassen und zu quantifizieren sowie an einem kleinen Kollektiv koronarkranker Patienten die prognostische Bedeutung abzuschätzen.Bei 26 Gesunden, 32 Patienten nach akutem Myokardinfarkt ohne maligne ventrikuläre Arrhythmien und 10 Patienten mit koronarer Herzkrankheit und anhaltender, monomorpher ventrikulärer Tachykardie in der Anamnese wurde in einem magnetisch abgeschirmten Raum eine Magnetokardiographie mittels Superconducting Quantum Interference Device (SQUID)-Elementen durchgeführt. Zur Quantifizierung der fragmentierten Aktivierung im QRS wurde ein Fragmentations-Index (FI) berechnet. Bei jedem Patienten bzw. Gesunden wurde außerdem ein hochverstärktes EKG zur Analyse von Spätpotentialen, bei den Patienten mit koronarer Herzkrankheit eine Herzkatheteruntersuchung und bei den Patienten mit ventrikulären Herzrhythmusstörungen eine elektrophysiologische Untersuchung durchgeführt.Es ergaben sich für die drei Gruppen hochsignifikant unterschiedliche Werte für den FI (p<0,005). Der mittlere FI in der Gruppe der Gesunden betrug 20,4±5,4, in der Gruppe der Postinfarkt-Patienten ohne Arrhythmien 27,2±12,1 und in der Gruppe der Patienten mit koronarer Herzkrankheit und ventrikulären Tachykardien 49,5±17,9. Bei einem Schwellenwert von 36 ergab sich eine Sensitivität von 80%, eine Spezifität von 93%, ein positiv prädiktiver Wert von 66% und ein negativ prädiktiver Wert von 96% bezüglich des Auftretens einer anhaltenden ventrikulären Tachykardie. Der Fragmentations-Index war korreliert mit dem Ausmaß der regionalen Wandbewegungsstörungen und der globalen linksventrikulären Ejektionsfraktion.Bei der Spätpotentialanalyse ergaben sich überraschend niedrige Werte für Sensitivität (20%) und positiv prädiktiven Wert (50%) bei einer Spezifität von 96% und einem negativ prädiktiven Wert von 88%. Bei der Errechnung des FI aus den elektrischen Signalen konnten die drei Gruppen nur unzureichend unterschieden werden.In der 2-jährigen Nachverfolgungsperiode der Postinfarkt-Patienten erlitt ein Patient Kammerflimmern und konnte erfolgreich reanimiert werden. Der FI dieses Patienten betrug 17.Ein Patient mit koronarer 3-Gefäß-Erkrankung verstarb an einem akuten Myokardinfarkt. Sein FI betrug 39.Schlußfolgerung: Mittels der Magnetokardiographie konnte eine fragmentierte ventrikuläre Aktivierung bei Patienten mit koronarer Herzkrankheit auch im QRS-Komplex nachgewiesen werden und zu abgelaufenen ventrikulären Tachykardien korreliert werden.SummaryFragmented and delayed activation of ventricular myocardium can cause malignant tachyarrhythmias. By detection of ventricular late potentials only a severely delayed depolarisation is registered, but not the intra QRS-activation. The aim of this study was to examine the complete phase of ventricular depolarisation, to detect and to quantify abnormal electrical activation by magnetocardiography and to estimate in a small group of patients with coronary heart disease the prognostic significance.In 26 healthy subjects, 32 patients after myocardial infarction without malignant ventricular arrhythmias and 10 patients with coronary heart disease and a history of sustained, monomorph ventricular tachycardia magnetocardiography was performed in a magnetically shielded room. To quantify the fragmentation of QRS a fragmentation-index (FI) was calculated. Besides signal averaged ECG, in patients with coronary heart disease cardiac catheterisation and in patients with arrhythmias electrophysiological testing was performed. The FI for the three groups was significantly different (p<0,005). The mean FI in the group of healthy subjects was 20,4±5,4, in the group of postinfarction-patients without arrhythmias 27±12,1 and in the group of patients with coronary heart disease and ventricular arrhythmias 49,5±17,9. Dichotomized at 36 the sensitivity was 80%, the specifity 93%, the positive predictive value was 66% and the negative predictive value 96%. The FI was correlated to the extent of regional wall-motion-irregularity and global ejection fraction.Analyzing late potentials, the values for sensitivity and positive predictive value were surprisingly low (20% and 50%, respectively). The specifity was 96%, the negative predictive value was 88%. Calculating the FI on the basis of electrical signals only an insufficient discrimination of the groups was possible.In the follow-up period of two years one post-infarctional patient was resusciated because of ventricular fibrillation. The FI of this patient was 17.One patient with coronary 3-vessel-disease and left ventricular ejection fraction of 50% died due to acute myocardial infarction, his FI was 39.Conclusion: By means of magnetocardiography fragmented ventricular activation in patients with coronary heart disease was demonstrated even within the QRS-complex and could be correlated to ventricular tachyarrhythmias.