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.

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.