Yonsei Med J.  2016 Nov;57(6):1339-1346. 10.3349/ymj.2016.57.6.1339.

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

• Bang WD
• Kim K
• Lee YH
• Kwon H
• Park Y
• Pak HN
• Ko YG
• Lee M
• Joung B

• KMID: 2427150
• DOI: http://doi.org/10.3349/ymj.2016.57.6.1339

Abstract

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.

Keyword

Acute myocardial infarction; prognosis; magnetocardiography

MeSH Terms

Aged
Aged, 80 and over
Female
Follow-Up Studies
Humans
*Magnetocardiography
Male
Middle Aged
Myocardial Infarction/*diagnosis
Predictive Value of Tests
Prognosis
Proportional Hazards Models
Republic of Korea
Sensitivity and Specificity

Figure

• 

  Fig. 1 Measurement of MCG. (A) MCG tracing. (B) Current vector density map. (C) Magnetic field map. Maximum current angle (C), field map angle (F), and the number and distance of poles (P) were measured every 20 ms from T-end (Te) to T-peak (Tp). MCG, magnetocardiography.

• 

  Fig. 2 Examples of dipole (A) and non-dipole pattern (B). The number of poles (P) is 2 and 4 in dipole and non-dipole patterns, respectively.

• 

  Fig. 3 Typical MCG finding from a 79-year-old female patient without MACE (A) and a 66-year-old female patient with MACE (B). MCG tracing (upper panels), spatiotemporal activation graph (middle panels), and magnetic field and current vector density maps (lower panels). While the dipole pattern was observed at Tp in the patient without MACE, the non-dipole pattern can be seen in the patient with MACE. Note continuous change and dispersion of the magnetic field from Tp to Te. MACE, major adverse cardiac events; MCG, magnetocardiography; Te, T-end; Tp, T-peak.

• 

  Fig. 4 MACE-free survival. Kaplan-Meier survival curves for cardiac events in patients with different repolarization patterns at Tp. Patients with non-dipole patterns at Tp had lower cumulative cardiac event-free survival than did the dipole pattern group (p=0.02). MACE, major adverse cardiac events; Tp, T-peak.

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