Division of Cardiology, Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.
Circ Cardiovasc Imaging. 2013 Jul;6(4):542-50. doi: 10.1161/CIRCIMAGING.111.000146. Epub 2013 Jun 5.
Transmural scar occupying left ventricular (LV) pacing regions has been associated with reduced response to cardiac resynchronization therapy (CRT). However, spatial influences of lead tip delivery relative to scar at both pacing sites remain poorly explored. This study evaluated scar distribution relative to LV and right ventricular (RV) lead tip placement through coregistration of late gadolinium enhancement MRI and cardiac computed tomographic (CT) findings. Influences on CRT response were assessed by serial echocardiography.
Sixty patients receiving CRT underwent preimplant late gadolinium enhancement MRI, postimplant cardiac CT, and serial echocardiography. Blinded segmental evaluations of mechanical delay, percentage scar burden, and lead tip location were performed. Response to CRT was defined as a reduction in LV end-systolic volume ≥15% at 6 months. The mean age and LV ejection fraction were 64±9 years and 25±7%, respectively. Mean scar volume was higher among CRT nonresponders for both the LV (23±23% versus 8±14% [P=0.01]) and RV pacing regions (40±32% versus 24±30% [P=0.04]). Significant pacing region scar was identified in 13% of LV pacing regions and 37% of RV pacing regions. Absence of scar in both regions was associated with an 81% response rate compared with 55%, 25%, and 0%, respectively, when the RV, LV, or both pacing regions contained scar. LV pacing region dyssynchrony was not predictive of response.
Myocardial scar occupying the LV pacing region is associated with nonresponse to CRT. Scar occupying the RV pacing region is encountered at higher frequency and seems to provide a more intermediate influence on CRT response.
透壁性瘢痕占据左心室（LV）起搏区域与心脏再同步治疗（CRT）反应降低有关。然而，相对于起搏部位的瘢痕，导线尖端输送的空间影响仍未得到充分探索。本研究通过心脏磁共振延迟钆增强成像（LGE-MRI）和心脏计算机断层扫描（CT）的核心配准，评估了瘢痕分布与 LV 和右心室（RV）导线尖端放置的关系。通过连续超声心动图评估 CRT 反应的影响。
60 例接受 CRT 的患者接受了心脏 MRI 延迟钆增强扫描、心脏 CT 扫描和连续超声心动图检查。对机械延迟、瘢痕负荷百分比和导线尖端位置进行了盲法节段评估。CRT 反应定义为 6 个月时 LV 收缩末期容积减少≥15%。患者平均年龄和 LV 射血分数分别为 64±9 岁和 25±7%。LV 和 RV 起搏区域的瘢痕体积在 CRT 无反应者中均较高（LV：23±23%比 8±14%，P=0.01；RV：40±32%比 24±30%，P=0.04）。在 13%的 LV 起搏区域和 37%的 RV 起搏区域发现明显的起搏区域瘢痕。当 RV、LV 或两者均存在瘢痕时，无瘢痕区域与 81%的反应率相关，而分别为 55%、25%和 0%。LV 起搏区域不同步不能预测反应。
占据 LV 起搏区域的心肌瘢痕与 CRT 无反应有关。RV 起搏区域存在瘢痕的频率更高，对 CRT 反应的影响似乎更居中。
