Guida Gianluigi, Sorbo Anna Rita, Fenici Riccardo, Brisinda Donatella
Biomagnetism and Clinical Physiology International Center, Catholic University of Sacred Heart, Rome, Italy.
Ann Noninvasive Electrocardiol. 2018 Nov;23(6):e12569. doi: 10.1111/anec.12569. Epub 2018 Jun 27.
P-wave duration, its dispersion and signal-averaged ECG, are currently used markers of vulnerability to atrial fibrillation (AF). However, since tangential atrial currents are better detectable at the body surface as magnetic than electric signals, we investigated the accuracy of magnetocardiographic mapping (MCG), recorded in unshielded clinical environments, as predictor of AF occurrence.
MCG recordings, in sinus rhythm (SR), of 71 AF patients and 75 controls were retrospectively analyzed. Beside electric and magnetic P-wave and PR interval duration, two MCG P-wave subintervals, defined P-dep and P-rep, were measured, basing on the point of inversion of atrial magnetic field (MF). Eight parameters were calculated from inverse solution with "Effective Magnetic Dipole (EMD) model" and 5 from "MF Extrema" analysis. Discriminant analysis (DA) was used to assess MCG predictive accuracy to differentiate AF patients from controls.
All but one (P-rep) intervals were significantly longer in AF patients. At univariate analysis, three EMD parameters differed significantly: in AF patients, the dipole-angle-elevation angular speed was lower during P-dep (p < 0.05) and higher during P-rep (p < 0.001) intervals. The space-trajectory during P-rep and the angle-dynamics during P-dep were higher (p < 0.05), whereas ratio-dynamics P-dep was lower (p < 0.01), in AF. At DA, with a combination of MCG and clinical parameters, 81.5% accuracy in differentiating AF patients from controls was achieved. At Cox-regression, the angle-dynamics P-dep was an independent predictor of AF recurrences (p = 0.037).
Quantitative analysis of atrial MF dynamics in SR and the solution of the inverse problem provide new sensitive markers of vulnerability to AF.
P波时限、其离散度以及信号平均心电图目前是用于预测心房颤动（AF）易感性的指标。然而，由于心房切线电流在体表以磁信号比电信号更易检测到，我们研究了在非屏蔽临床环境中记录的磁心动图（MCG）作为AF发生预测指标的准确性。
回顾性分析了71例AF患者和75例对照者在窦性心律（SR）时的MCG记录。除了电和磁P波及PR间期时限外，基于心房磁场（MF）反转点测量了两个MCG P波子间期，定义为P-dep和P-rep。用“有效磁偶极子（EMD）模型”从逆解中计算了8个参数，用“MF极值”分析计算了5个参数。采用判别分析（DA）评估MCG区分AF患者与对照者的预测准确性。
除一个间期（P-rep）外，AF患者的所有间期均显著更长。在单变量分析中，三个EMD参数有显著差异：在AF患者中，P-dep期间偶极角仰角角速度较低（p<0.05），P-rep期间较高（p<0.001）。AF患者中，P-rep期间的空间轨迹和P-dep期间的角度动态更高（p<0.05），而P-dep期间的比率动态更低（p<0.01）。在DA分析中，结合MCG和临床参数，区分AF患者与对照者的准确率达到81.5%。在Cox回归分析中，P-dep期间的角度动态是AF复发的独立预测因素（p=0.037）。
SR时心房MF动态的定量分析及逆问题的求解提供了新的AF易感性敏感指标。
