冠心病患者碎裂QRS波的发生机制及心肌力学特征研究

In patients with coronary artery disease (CAD) with or without prior myocardial infarction, the fQRS complex predicted the occurrence of adverse clinical outcomes and sudden cardiac death. Though the potential mechanisms of fQRS complex have been implicated in the myocardial fibrosis of the ventricles due to myocardial scar and/or ischemia, only about one-third of the CAD patients with fQRS. The exact mechanism of fQRS complex in the 12-lead surface ECG is still unclear. Moreover，the myocardium mechanical characteristics for CAD patients with fQRS and relationship between myocardial fibrosis and myocardial mechanics characteristics are suspense. In our preliminary study，CAD patients with fQRS complex had a significantly decreased mechanical deformation function measured by using 2D speckle-tracking imaging, including longitudinal, radial, circumferential strains and strain rates. Furthermore, 2D circumferential strain was significantly associated with the fQRS complex, independent of history of MI and other echocardiographic parameters, including LV systolic and diastolic functions and regional wall motion abnormalities. In addition, the fQRS complex was an independent predictor for increased cardiac events in patients with CAD. In this study，we will further identify the mechanism of fQRS complex in CAD patients, to determine the relationship between the myocardial fibrosis degree and fQRS complex. Further explore cardiac functional effects followed by fQRS，which will provide experimental evidence for detection the degree of myocardial fibrosis by ultrasound.

碎裂QRS波对冠心病患者不良临床预后和心脏猝死有很好的预测价值。尽管心肌纤维化、瘢痕形成及心肌缺血是冠心病患者产生fQRS波的最重要原因，但是大约只在1/3左右冠心病患者中发现fQRS波，其与心肌纤维化程度的关系尚未明确。而且fQRS波与心肌力学特征的关系还有待研究。本课题组前期对伴有fQRS波的冠心病患者进行了心肌运动特征的部分研究，发现fQRS阳性的患者心肌应变降低、存在左室内收缩不同步，而且心脏事件死亡率增高。因此本课题将：进一步明确fQRS波形成机制，确定心肌纤维化与fQRS波的关系。探索fQRS波对心肌力学、心脏功能的影响，为超声技术检测心肌纤维化提供可靠的实验依据。

碎裂QRS波对冠心病患者不良临床预后和心脏猝死有很好的预测价值。尽管心肌纤维化、瘢痕形成及心肌缺血是冠心病患者产生fQRS波的最重要原因，但是大约只在1/3左右冠心病患者中发现fQRS波，其与心肌纤维化程度的关系尚未明确。而且fQRS波与心肌力学特征的关系还有待研究。因此本课题应用超声分层应变、四维应变、心脏磁共振延迟成像等技术结合血清学心肌纤维化标志物进一步明确fQRS波形成机制，确定心肌纤维化与fQRS波的关系。探索fQRS波对心肌力学、心脏功能的影响，为超声技术检测心肌纤维化提供可靠的实验依据。本研究发现fQRS阳性冠心病患者Gensini积分明显高于fQRS阴性组，且冠状动脉多支病变发生率明显增高。超声心动图显示fQRS阳性组左室舒张末内径及收缩末内径明显大于fQRS阴性组，而射血分数明显降低（P＜0.05）。二维分层应变显示，无论有无fQRS其相应供血左心室心肌节段LSendo、LSmid、LSepi和CSendo、CSmid、CSepi均呈梯度递减；与fQRS阴性组比较，fQRS阳性组LSendo、LSmid、CSmid及纵向应变跨壁梯度（△LS）均显著减低（P＜0.05），而LSepi、CSendo、CSepi及圆周应变跨壁梯度减低，但差异无统计学意义。fQRS阳性组四维应变指标GLS、GCS、GAS较fQRS阴性组均明显减低（P＜0.05）。心脏磁共振LGE检测，fQRS阳性组的LGE体积及LGE质量大于fQRS阴性组，但差异无统计学意义。fQRS阳性组心肌纤维化血清标志物PIIINP、PICP及HA明显高于阴性组。相关性分析显示四维应变指标（GLS、GAS）及△LS与PIIINP、PICP相关。多因素分析结果显示，冠脉多支病变、△LS、GAS、GLS、PIIINP、PICP是fQRS的独立危险因素。结论：左心室射血分数正常fQRS冠心病患者四维应变及二维分层应变的相关应变参数可用来预测fQRS的发生，并能作为新的超声诊断指标来评估患者的心肌纤维化程度。