Discussion on Technical Evaluation of Magnetocardiography / 中国医疗器械杂志

There is no corresponding product standard and industry standard for the search and development of magnetocardiograph at home and abroad. In this paper, based on the working principle and clinical application function of magnetocardiograph, and on the basis of relevant regulations and normative documents of medical device registration, some thoughts and concerns about the technical review of this kind of product are put forward.

Repolarization Heterogeneity of Magnetocardiography Predicts Long-Term Prognosis in Patients with Acute Myocardial Infarction

No abstract available.

Repolarization Heterogeneity of Magnetocardiography Predicts Long-Term Prognosis in Patients with Acute Myocardial Infarction

PURPOSE: Magnetocardiography (MCG) has been proposed as a noninvasive, diagnostic tool for risk-stratifying patients with acute myocardial infarction (AMI). This study evaluated whether MCG predicts long-term prognosis in AMI. MATERIALS AND METHODS: In 124 AMI patients (95 males, mean age 60±11 years), including 39 with ST-elevation myocardial infarction, a 64-channel MCG was performed within 2 days after AMI. During a mean follow-up period of 6.1 years, major adverse cardiac events (MACE) were evaluated. RESULTS: MACE occurred in 31 (25%) patients, including 20 revascularizations, 8 deaths, and 3 re-infarctions. Non-dipole patterns were observed at the end of the T wave in every patients. However, they were observed at T-peak in 77% (24/31) and 54% (50/93) of patients with and without MACE, respectively (p=0.03). Maximum current, field map angles, and distance dynamics were not different between groups. In the multivariate analysis, patients with non-dipole patterns at T-peak had increased age- and gender-adjusted hazard ratios for MACE (hazard ratio 2.89, 95% confidence interval 1.20–6.97, p=0.02) and lower cumulative MACE-free survival than those with dipole patterns (p=0.02). CONCLUSION: Non-dipole patterns at T-peak were more frequently observed in patients with MACE and were related to poor long-term prognosis. Thus, repolarization heterogeneity measured by MCG may be a useful predictor for AMI prognosis.

Diagnostic value of magnetocardiography in patients with coronary heart disease and in-stent restenosis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>In-stent restenosis (ISR) has become one of the most challenging problems in patients with coronary heart disease. At present, using non-invasive methods to assess ISR is a hot topic. In this investigation we attempted to explore the potential of magnetocardiography (MCG) in diagnosis of in-stent restenosis.</p><p><b>METHODS</b>MCG was analyzed in 52 patients with coronary artery disease for three times: before stenting, one month and 7 months after successful intracoronary stenting.</p><p><b>RESULTS</b>The average classification of total maps (ACTM) and the ratio of abnormal maps (RAM) were lower in 1 month after intracoronary stenting compared with that obtained before stent planting (2.91 vs 2.52, 65.74% vs 42.80%, P < 0.01), while complex ventricular excitation index (CVEI) increased from -42.63 to -20.05 (P < 0.01). In ISR subgroup (n = 16), RAM decreased in 1 month after intracoronary stenting compared to it before stenting (68.99% vs 45.26%, P < 0.05). ACTM increased in 7 months compared to that obtained in 1 month after stenting (3.15 vs 2.51, P < 0.05). According to the ROC curve, ACTM showed its unique diagnostic value in restenosis patients. The sensitivity and specificity of ACTM were 80.0%, 69.40%, respectively. Its positive predictive value and negative predictive value were 54.6% and 88.5%, respectively.</p><p><b>CONCLUSIONS</b>After successful intracoronary stenting, most parameters of MCG were improved. ACTM was of prognostic value in diagnosing ISR.</p>

Magnetocardiography changes in coronary artery disease patients with normal or unspecialized resting electrocardiogram / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the magnetocardiography (MCG) changes in coronary artery disease (CAD) patients with normal or unspecific changes in resting electrocardiogram (ECG).</p><p><b>METHODS</b>MCG mapping was performed by MCG-7 (MaGIC, Magiscan GmbH) installed in an unshielded room. All patients underwent ECG and coronary angiogram examinations and patients with normal or unspecified ECG changes and coronary artery narrowing > or = 70% in at least 1-vessel were defined as CAD group (n = 120). Patients with normal coronary angiogram served as control (n = 82). Four parameters: ACTM (average classification of total maps), RAM (ratio of abnormal maps), CVEI (complex ventricular excitation index) and R-max/T-max ratio, were analyzed in CAD and control groups.</p><p><b>RESULTS</b>RAM (62% vs. 35%) and ACTM (2.62 +/- 0.98 vs. 2.29 +/- 0.90, P < 0.05) were significantly higher in CAD group than in control group. CVEI was found in abnormal zone (-100 - 0) in CAD group while in normal zone (0 - 100) in control group. The ratio of Rmax/Tmax in CAD group was also significantly higher in CAD group than in control group (6.41 +/- 3.29 vs. 4.10 +/- 2.00, P < 0.01). ROC curve analysis indicates that RAM, CVEI and Rmax/Tmax ratio were helpful parameters for CAD diagnosis and the diagnostic sensitivity was 67.1%, 65.9% and 64.3%; the specificity was 65.1%, 68.3% and 68.3% respectively.</p><p><b>CONCLUSION</b>MCG was a useful tool for diagnosing chronic myocardium ischemia in CAD patients with normal or unspecific changes resting ECG.</p>

Magnetocardiography in Coronary Artery Disease with Nonspecific Electrocardiographic Finding

BACKGROUND AND OBJECTIVE: Magnetocardiography (MCG) is a noninvasive method for the registration of the magnetic component of electromagnetic fields in the heart that arise from electrical activity during the cardiac cycle. It has a theoretical advantage, over ECG, for the detection of coronary artery disease (CAD), mainly due to its higher sensitivity for local currents and better spatial resolution. However, its clinical value in the diagnosis of CAD, compared to other diagnostic tools, remains untested. The feasibility of MCG for detecting myocardial ischemia was studied. SUBJECTS AND METHODS: Ninety three patients (54 male, 39 female) with chest pain were enrolled in this study. Patients with a pacemaker or other metal implants, as well as those in unstable conditions, were excluded. Coronary angiography was performed on all the patients, following ECG and MCG measurements, on the same day. Coronary artery disease was diagnosed when intraluminal narrowing was greater than 70%. The ECG and MCG findings were compared to those of the coronary angiography, which was used as the gold standard. RESULTS: Forty two patients were diagnosed with CAD by the coronary angiography. The sensitivities and specificities of MCG and ECG for detecting a CAD were 76.2 and 47.1%, and 38.1 and 86.3%, respectively. Seventy patients showed non-diagnostic ECG for CAD. The sensitivity and specificity of MCG for detecting a CAD in this group of patients were 69.2 and 52.3%, respectively. CONCLUSION: MCG is a novel noninvasive technique for the diagnosis of coronary artery disease, but further investigation for the optimization of the efficacy of this technology will be required.

Sequential changes of magnetocardiogram in rat models of experimental myocardial infarction / 대한내과학회지

BACKGROUND: Magnetocardiogram (MCG), which records the changes of magnetic fields generated by the heart's electrical activity, theoritically can provide unique data for clinical application. To date, MCG has been investigated only at a single time point after myocardial infarction (MI) with severe left ventricular dysfunction in rats. The purpose of the present study was to investigate sequential changes of MCG after MI and to evaluate effects of infarct size on MCG. METHODS: Acute MI were induced by the permanent ligation of left coronary artery in 22 rats. Magnetic fields were recorded just above a rat with Nb Superconducting Quantum Interference Device (SQUID) gradiometer inside a magnetically shielded room. MCG was measured before and immediately after surgery and it was subsequently recorded at the time points of 1, 4 and 6 hours postoperatively. MCG was also measured at 1, 3, 7 and 21 days after surgery. RESULTS: Elevation of ST segment and appearance of pathological Q wave on the MCG were evident immediately after the ligation of coronary artery and persisted to 6 hours after MI. On MCG, ST segment was depressed and T wave was inverted from 1 day after MI. In rats with small- and moderate-sized MI (infarct size or = 30%). CONCLUSION: Evolutional changes of MCG were well-recognized up to 21 days after MI. Furthermore, the infarct size can be expressed by the extent of Q wave and ST segment depression on MCG. Taken together, these data indicate that MCG is a helpful modality for the diagnosis, evaluation of infarct size and follow up after MI.