Galichia Heart Hospital, 2600 N. Woodlawn Avenue, Wichita, KS 67226, USA.
Europace. 2010 Mar;12(3):385-8. doi: 10.1093/europace/eup408. Epub 2010 Jan 3.
Advanced cardiac disease, entailing more hypertrophy, fibrosis, scarring, dilatation and conduction delays, poses the question of whether defibrillation thresholds (DFTs) increase as left ventricular ejection fraction (LVEF) decreases. This question has been approached indirectly or insufficiently in previous studies. In this study we add and expand on our previous work, stratifying DFT for various LVEF ranges.
This retrospective analysis included DFT data from three acute, multicentre, randomized studies that included 230 ICD/CRT-D patients. All DFTs were obtained with the SVC coil turned ON and with pulse-width optimized waveforms based on a 3.5 ms membrane time constant. As the LVEF decreased, DFT estimates increased from 395.2 +/- 115 V for LVEF > or = 46% to 425.8 +/- 117.6 V for LVEF < or = 25%. However, these changes in DFT estimates were very minor and not statistically significant. Only 3% of the patients in this population had an elevated DFT of >20 J.
This analysis shows that over a very broad range of LVEF, DFT changes minimally (approximately 1 J), if at all. Our results are consistent with previous studies that demonstrated no difference in the DFT estimates: (a) between patient groups receiving ICD (typically higher LVEF) vs. CRT-D (typically lower LVEF) and (b) between patient groups receiving a device for primary prevention indications (typically lower LVEF) vs. secondary prevention indications (typically higher LVEF).
涉及更严重肥大、纤维化、瘢痕形成、扩张和传导延迟的晚期心脏疾病提出了一个问题，即随着左心室射血分数（LVEF）降低，除颤阈值（DFT）是否会增加。这个问题在以前的研究中被间接或不充分地探讨过。在这项研究中，我们在之前的工作基础上进行了补充和扩展，对各种 LVEF 范围进行了 DFT 分层。
这项回顾性分析包括来自三个急性、多中心、随机研究的 DFT 数据，共有 230 例 ICD/CRT-D 患者。所有 DFT 均在 SVC 线圈开启的情况下，使用基于 3.5ms 膜时间常数的优化脉冲宽度的波形获得。随着 LVEF 的降低，DFT 估计值从 LVEF>或=46%的 395.2+/-115V 增加到 LVEF<或=25%的 425.8+/-117.6V。然而，这些 DFT 估计值的变化非常小，且无统计学意义。在该人群中，只有 3%的患者 DFT 升高>20J。
这项分析表明，在非常广泛的 LVEF 范围内，DFT 的变化很小（约 1J），如果有的话。我们的结果与以前的研究一致，这些研究表明 DFT 估计值没有差异：（a）在接受 ICD（通常 LVEF 较高）和 CRT-D（通常 LVEF 较低）的患者组之间，以及（b）在接受设备用于一级预防适应症（通常 LVEF 较低）和二级预防适应症（通常 LVEF 较高）的患者组之间。
