The present study aimed to develop a computerized classification of magnetocardiograms (MCG) on the basis of current density vectors (CDV) map analysis for the diagnosis of coronary artery disease (CAD). The study included 123 patients with angina and angiographically documented CAD but with normal ECG at rest and normal left ventricular function. The control group consisted of 124 normals. 4-channel SQUID-magnetometer systems located in an unshielded hospital environment was used. MCG recordings were taken at 36 pre-thoracic sites over the pericardial area and reconstruction of CDV maps within the ST–T interval was applied. Each CDV map was classified automatically with a scale from 0 (normal) to 4 (grossly abnormal). The classification number depends on the number of large vectors directed left–downward and the presence of additional clusters. The mean class was calculated for each subject in order to discriminate between groups. Using a mean class value of 1.75 as threshold for the discrimination between healthy persons and CAD patients, 76% sensitivity and 81% specificity were achieved. The computerized classification of CDV maps seems to be a useful tool for the diagnosis of CAD.

Background: The noninvasive detection of restenosis after percutaneous coronary intervention (PCI) remains a clinical challenge. Previous studies have shown that magnetocardiograms reveal obvious changes in patients with coronary artery disease (CAD) and normal electrocardiogram (ECG) at rest. Hypothesis: The present study aimed to evaluate the potential of magnetocardiography (MCG) for the detection of electrophysiological changes in the course of successful PCI. Methods: Twelve‐lead ECG and unshielded four‐channel MCG (SQUID AG, Essen, Germany) were registered at nine prethoracic sites in 50 patients with CAD (62 10 years; EF = 76 11%; registration: before, 24 hours, and 1 month (n = 25) after PCI) and 57 normals (51 9 years). Current density vector (CDV) maps were reconstructed within the ST–T interval and classified from category 0 (normal) to category 4 (grossly abnormal). In both groups and at all registration times, the percentage of each category of maps was calculated and compared. Results: Most CDV maps of normals were classified as category 0, 1, or 2 compared to CAD patients before PCI with most maps of category 3 and 4 (P < 0.0005). Twenty‐four hours after PCI, more maps were classified as category 2 (P < 0.05) and less as category 4 (P < 0.005). One month after PCI the MCG results further improved: more maps were classified as category 1 (P < 0.05) and 2 (P < 0.005) and less maps as category 4 (P < 0.0001). The ECG remained unchanged in the course of PCI. Conclusion: Unshielded four‐channel MCG reveals obvious changes in the course of successful PCI on the basis of CDV map reconstruction during repolarization. The method seems to be suitable for the follow‐up of patients after PCI.

BACKGROUND:The diagnostic management of patients with chest pain remains a clinical challenge. Magnetocardiography (MCG) is a noninvasive method for the recording of cardiac electromagnetic signals at multiple sites above the chest cage. Contrary to electrocardiogram (ECG) the magnetic field is unaltered by surrounding tissues. The present study aimed to analyze the diagnostic value of an unshielded four-channel MCG for the detection of coronary artery disease (CAD) in patients with chest pain. METHODS:The study included 417 subjects: 177 patients with angiographically documented CAD (stenoses > or =50%), 123 symptomatic patients without hemodynamically relevant stenosis (nCAD) and 117 healthy subjects. Twelve-lead ECG was obtained in all subjects. The magnetocardiography recordings were taken from 36 positions at rest. From these current density vector maps were generated during the ST-T interval. Each map was classified using a classification system with a scale from 0 (normal) to 4 (grossly abnormal). RESULTS:While the ECG was normal in all subjects the MCG revealed typical differences. In normals most maps were classified as category 0, 1 or 2, in nCAD and more so in CAD patients the categories 3 and 4 prevailed. Using a cut-off value of 39.2% for the discrimination between normals and CAD patients sensitivity was 73.3%, specificity 70.1%. CONCLUSION:Contrary to ECG, unshielded MCG reveals significant differences between normals and symptomatic patients with and without relevant stenoses using current density reconstruction during repolarization at rest. This method might be a suitable noninvasive tool for the management of patients with chest pain.

Background: The noninvasive detection of coronary artery disease (CAD) remains a clinical challenge. Magnetocardiography is a completely noninvasive method that permits the registration of cardiac electrical activity at multiple sites in a plane above the chest cage without the need for electrodes. In contrast to the electrocardiogram (ECG) which suffers from boundary effects and a variety of potential artifacts (electrode placement, etc.) the MCG is unaffected by such impediments as the magnetic field is unaltered by surrounding tissues.Hypothesis: Magnetocardiography with a newly developed single-channel system in an unshielded setting should be a better qualitative diagnostic tool than the standard ECG for the detection and assessment of CAD.Methods: In all, 52 patients with angiographically documented CAD and unimpaired ventricular function as well as 55 controls were included in this study. A standard 12-lead ECG was obtained in all subjects. The MCG recordings were taken from 36 positions under resting conditions. From these, current density vector maps were generated during the ST-T interval. Each map was then classified using a classification system with a scale from 0 (normal) to 4 (grossly abnormal).Results: While the ECG was normal in all subjects, the MCG in the controls was classified as category 0, 1, or 2. However, in patients with abnormal coronary angiograms, mainly maps in categories 3 and 4 were seen (p < 0.05).Conclusion: A single-channel magnetometer in an unshielded setting reveals significant differences between normals and patients with CAD with normal ECG on the basis of current density reconstruction during the ST segment when measured under resting conditions. This method might be suitable for the noninvasive detection of CAD.

During recent years, percutaneous transluminal coronary angioplasty (PTCA) has developed to the most often applied therapeutical method in coronary artery disease (CAD) even in cases with complex stenosis. Since the beginning of interventional therapy there is need for a noninvasive method to follow up PTCA results, especially because of the number of restenosis mainly in the first six months following PTCA or coronary stenting and the increasing costs and possible side effects of invasive procedures. At present there is no “gold standard” for detecting restenosis, as sensitivity and specificity of noninvasive diagnostical methods in clinical routine for detecting myocardial ischemia like stress tests, nuclear imaging or positrons emission tomography do not allow to clearly identify patients with coronary restenosis after PTCA.[1] Today magnetocardiography (MCG), as a method of non-contact registration and analysis of the magnetic field of the human heart, seems to be useful as a noninvasive method for detecting CAD. In previous studies MCG proved its high sensitivity to local currents, why it is promising to be an additional method to detect myocardial ischemia. [2; 3] MCG analysis can be performed using the inverse electrodynamic problem solution, which implies the reconstruction of electrical events in the heart on the basis of registration carried out on the surface of human body. The detection of so called tangential injury currents was possible on the bases of MCG. Our study aimed to investigate the ability of MCG to detect electrophysiological changes in CAD patients after PTCA using current density reconstruction.

The noninvasive diagnosis of coronary artery disease remains a clinical challenge. Electrocardiogram (ECG) at rest is frequently normal in these patients and the predictive value of stress methods and nuclear imaging is often limited and may be associated with risk. Magnetocardiography (MCG) is known as a fully noninvasive method to measure cardiac activity. Various studies have confirmed that MCG may give additional information compared to 12 lead ECG [1]. However, the acceptance of the method in clinical practice is limited with regard to the expensive installation of the system inside a shielded location. The aim of our study is the investigation of the potential og MCG on the basis of inverse problem solution in patients with CAD and normal or unspecific changes in resting ECG using a system in unshielded location.

Article EINE NICHTINVASIVE METHODE, DEN ERFOLG VON PTCA-ERGEBNISSEN ZU VERFOLGEN was published on January 1, 2001 in the journal Biomedical Engineering / Biomedizinische Technik (volume 46, issue s1).

MCG examinations were performed using a single-channel SQUID-magnetometer in unshielded location in patients with CAD and normal or unspecifically changed resting EGG. Current distribution maps within ST-T interval have been observed. Possibilities of unshielded MCG to ischemia detection and quantification have been shown.