心电图正常或呈非特异性改变的冠心病患者心磁图分析

Magnetocardiography changes in coronary artery disease patients with normal or unspecialized resting electrocardiogram

目的 探讨心磁图（Magnetocardiography，MCG）对于静息心电图表现正常或呈非特异性改变的冠心病患者的诊断价值并筛选实用的诊断指标。方法 采用德国Magscan公司生产无屏蔽式MCGG记录仪，选择平均分级（average classification of total maps，ACTM）、异常心磁图所占百分比（ratio of abnormal maps，RAM）、复合心室激动指数（complex ventricular excitation index，CVEI）以及R波与T波的最大磁场值比值（Rmax／Tmax）四个分析指标，比较冠心病组（n=140，冠状动脉造影提示至少一支冠状动脉狭窄〉／70％）与对照组（n=2例，冠状动脉造影显示冠状动脉完全正常）的MCG结果。结果 冠心病组异常磁图的比例达到62％，多数电流密度图无明显双极对称结构，而对照组异常磁图的比例为35％，电流密度图有明显双极对称结构。冠心病组平均分级（2．62±0．98）显著高于对照组（2．29±0．90）。冠心病组的CVEI值位于异常区域（-100～0）内，而对照组CVEI值位于正常区域内（0～100）。Rmax／Tmax的比值在冠心病组高于对照组（6．41±3．29比4．10±2．00）。上述指标两组间差异均有统计学意义（P≤0．05）。通过受试者工作特征曲线（ROC曲线）分析表明，RAM、CVEI及Rmax／Tmax的诊断价值相对较高，敏感性分别为67．1％，65．9％及64．3％。特异性分别为65．1％，68．3％及68．3％。结论 MCG对于静息心电图表现正常或呈非特异性改变者的慢性心肌缺血患者有独特的诊断价值，有利于冠心病的早期诊断。

Objective To investigate the magnetocardiography （MCG） changes in coronary artery disease （CAD） patients with normal or unspecific changes in resting electrocardiogram （ECG）. Methods MCG mapping was performed by MCG-7 （ MAGIC, Magscan 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 ≥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. Results 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. Conclusion MCG was a useful tool for diagnosing chronic myocardium ischemia in CAD patients with normal or unspecific changes resting ECG.