Chen Yongle, Cheng Leilei, Yao Haohua, Chen Haiyan, Wang Yongshi, Zhao Weipeng, Pan Cuizhen, Shu Xianhong
Department of Echocardiography, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai Institute of Medical Imaging, Shanghai, PR China.
PLoS One. 2014 Dec 3;9(12):e113992. doi: 10.1371/journal.pone.0113992. eCollection 2014.
Evidence-based criteria for applying cardiac resynchronization therapy (CRT) in patients with ischemic cardiomyopathy are still scarce. The aim of the present study was to evaluate the predictive value of real-time myocardial contrast echocardiography (RT-MCE) in a preclinical canine model of ischemic cardiomyopathy who received CRT. Ischemic cardiomyopathy was produced by ligating the first diagonal branch in 20 beagles. Dogs were subsequently divided into two groups that were either treated with bi-ventricular pacing (CRT group) or left untreated (control group). RT-MCE was performed at baseline, before CRT, and 4 weeks after CRT. Two-dimensional speckle tracking imaging was used to evaluate the standard deviation of circumferential (Cir12SD), radial (R12SD), and longitudinal (L12SD) strains of left ventricular segments at basal as well as middle levels. Four weeks later, the Cir12SD, R12SD, and myocardial blood flow (MBF) of the treated group were significantly improved compared to their non-CRT counterparts. Furthermore, MBF values measured before CRT were significantly higher in responders than in non-responders to bi-ventricular pacing. Meanwhile, no significant differences were observed between the responder and non-responder groups in terms of Cir12SD, R12SD, and L12SD. A high degree of correlation was found between MBF values before CRT and LVEF after CRT. When MBF value>24.9 dB/s was defined as a cut-off point before CRT, the sensitivity and specificity of RT-MCE in predicting the response to CRT were 83.3% and 100%, respectively. Besides, MBF values increased significantly in the CRT group compared with the control group after 4 weeks of pacing (49.8±15.5 dB/s vs. 28.5±4.6 dB/s, p<0.05). Therefore, we considered that myocardial perfusion may be superior to standard metrics of LV synchrony in selecting appropriate candidates for CRT. In addition, CRT can improve myocardial perfusion in addition to cardiac synchrony, especially in the setting of ischemic cardiomyopathy.
在缺血性心肌病患者中应用心脏再同步治疗（CRT）的循证标准仍然匮乏。本研究的目的是评估实时心肌对比超声心动图（RT-MCE）在接受CRT的缺血性心肌病临床前犬模型中的预测价值。通过结扎20只比格犬的第一对角支制造缺血性心肌病。随后将犬分为两组，一组接受双心室起搏治疗（CRT组），另一组不治疗（对照组）。在基线、CRT前和CRT后4周进行RT-MCE。使用二维斑点追踪成像评估左心室基底段和中间段圆周（Cir12SD）、径向（R12SD）和纵向（L12SD）应变的标准差。4周后，与未接受CRT的对应组相比，治疗组的Cir12SD、R12SD和心肌血流量（MBF）显著改善。此外，双心室起搏反应者CRT前测量的MBF值显著高于无反应者。同时，反应者和无反应者组在Cir12SD、R12SD和L12SD方面未观察到显著差异。发现CRT前的MBF值与CRT后的左心室射血分数（LVEF）之间存在高度相关性。当将CRT前MBF值>24.9 dB/s定义为截断点时，RT-MCE预测CRT反应的敏感性和特异性分别为83.3%和100%。此外，起搏4周后，CRT组的MBF值与对照组相比显著增加（49.8±15.5 dB/s对28.5±4.6 dB/s，p<0.05）。因此，我们认为在选择CRT的合适候选者时，心肌灌注可能优于左心室同步性的标准指标。此外，CRT除了改善心脏同步性外，还可改善心肌灌注，尤其是在缺血性心肌病的情况下。
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