Azienda Ospedaliera Universitaria, Ferrara and Fondazione Salvatore Maugeri, Brescia, Italy.
Int J Cardiol. 2013 Jul 15;167(1):94-101. doi: 10.1016/j.ijcard.2011.12.006. Epub 2012 Jan 4.
In patients with ischemic heart failure undergoing cardiac resynchronization therapy (CRT) the underlying myocardial substrate at the left ventricle (LV) pacing site may affect CRT response. However, the effect of delivering the pacing stimulus remote, adjacent to or over LV transmural scar tissue (TST) identified by echocardiography is still unknown.
First, 35 patients with healed myocardial infarction (57 ± 11 years) were prospectically studied to demonstrate the capability of echocardiographic end-diastolic wall thickness (EDWT) to identify LV-TST as defined by delayed enhancement magnetic resonance imaging (DE-MRI). Subsequently, in 136 patients (65 ± 10 years) who underwent CRT, EDWT was retrospectively evaluated at baseline. The LV catheter placement was defined over, adjacent to and remote from TST if pacing was delivered at a scarred segment, at a site 1 segment adjacent to or remote from scarred segments. CRT response was defined as LV end-systolic volume (ESV) decrease by at least 10% after 6 months.
A EDWT ≤ 5mm identified TST at DE-MRI with 92% sensitivity and 96% specificity. In the 76 CRT responders, less overall and posterolateral TST segments and more segments paced remote from TST areas were found. At the multivariate regression analysis, the number of TST segments and scar/pacing relationship showed a significant association with CRT response.
In addition to LV global scar burden, CRT response relates also to the myocardial substrate underlying pacing site as evaluated by standard echocardiography. This information may expand the role of echocardiography to guide pacing site avoiding pacing at TST areas.
在接受心脏再同步治疗（CRT）的缺血性心力衰竭患者中，左心室（LV）起搏部位的潜在心肌基质可能会影响 CRT 反应。然而，通过超声心动图识别的 LV 透壁瘢痕组织（TST）起搏刺激远程、相邻或覆盖起搏刺激的效果尚不清楚。
首先，前瞻性研究了 35 例愈合性心肌梗死患者（57±11 岁），以证明超声心动图舒张末期壁厚度（EDWT）识别 LV-TST 的能力，LV-TST 由延迟增强磁共振成像（DE-MRI）定义。随后，回顾性评估了 136 例接受 CRT 的患者（65±10 岁）的基线 EDWT。如果起搏部位位于瘢痕部位或瘢痕部位 1 个节段的相邻或远处，则 LV 导管放置被定义为覆盖、相邻或远离 TST。CRT 反应定义为 6 个月后 LV 收缩末期容积（ESV）至少减少 10%。
EDWT≤5mm 可在 DE-MRI 上以 92%的敏感性和 96%的特异性识别 TST。在 76 例 CRT 反应者中，发现整体和后外侧 TST 节段较少，远离 TST 区域起搏的节段较多。在多变量回归分析中，TST 节段数量和瘢痕/起搏关系与 CRT 反应有显著相关性。
除了 LV 整体瘢痕负荷外，CRT 反应还与起搏部位的心肌基质有关，这可以通过标准超声心动图进行评估。这些信息可能会扩大超声心动图的作用，以指导起搏部位，避免在 TST 区域起搏。
