Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
Am Heart J. 2011 Jun;161(6):1060-6. doi: 10.1016/j.ahj.2011.03.014. Epub 2011 May 11.
Cardiac resynchronization therapy (CRT) has emerged as a treatment option for patients with end-stage heart failure and a QRS duration ≥120 ms. Nonetheless, many patients with a prolonged QRS do not demonstrate left ventricular (LV) mechanical dyssynchrony, and discrepancies between electrical and mechanical dyssynchrony have been observed. In addition, several studies demonstrated that superior benefits after CRT could be achieved when the LV pacing lead was positioned at the most delayed myocardial segment.
A total of 248 heart failure patients scheduled for CRT were included. In all patients, a 12-lead electrocardiogram and 2-dimensional echocardiogram were obtained. Patients were divided into 5 QRS configuration subgroups: narrow, left bundle-branch block, right bundle-branch block, intraventricular conduction delay, and right ventricular pacing. With speckle-tracking radial strain analysis, we evaluated time to peak radial strain. Next, the segments with the least and with the most mechanical activation delay were identified, and LV dyssynchrony was defined as the time delay between the two.
Mean QRS duration was 164 ± 31 ms. Mean LV dyssynchrony in all patients was 186 ± 122 ms. Site of latest activation was predominantly located in the lateral (27%), posterior (26%), and inferior (20%) segments. Furthermore, extent of LV dyssynchrony was comparable between QRS configuration subgroups. An unequal distribution of LV segments with the most mechanical delay was observed in the left bundle-branch block and right ventricular pacing subgroups (P < .001 for both), whereas in the narrow, right bundle-branch block, and intraventricular conduction delay subgroups, a more homogeneous distribution was noted. No differences in distribution pattern or in extent of LV dyssynchrony were observed between ischemic and nonischemic heart failure patients.
The lateral, posterior, and inferior segments take up 73% of the total latest activated segments in heart failure patients eligible for CRT. Presence of LV dyssynchrony can be observed in all QRS configurations. The site of latest activation may be outside the lateral or posterior segment, making echocardiographic assessment of LV dyssynchrony and site of latest activation a valuable technique to optimize patient outcome after CRT.
心脏再同步治疗（CRT）已成为伴有 QRS 时限≥120ms 的终末期心力衰竭患者的一种治疗选择。然而，许多 QRS 延长的患者并未表现出左心室（LV）机械不同步，并且已经观察到电和机械不同步之间存在差异。此外，多项研究表明，当 LV 起搏导线放置在延迟最明显的心肌节段时，CRT 后可获得更好的效果。
共纳入 248 例拟行 CRT 的心力衰竭患者。所有患者均行 12 导联心电图和二维超声心动图检查。患者分为 5 种 QRS 形态亚组：窄 QRS 波群、左束支传导阻滞、右束支传导阻滞、室内传导延迟和右心室起搏。采用斑点追踪径向应变分析，评估达峰径向应变时间。然后，确定机械激活延迟最小和最大的节段，并将其时间延迟定义为 LV 不同步。
平均 QRS 时限为 164±31ms。所有患者的平均 LV 不同步为 186±122ms。最晚激活部位主要位于外侧（27%）、后侧（26%）和下侧（20%）节段。此外，不同 QRS 形态亚组的 LV 不同步程度相当。左束支传导阻滞和右心室起搏亚组 LV 机械延迟最大节段的分布不均（两者均 P<0.001），而在窄 QRS 波群、右束支传导阻滞和室内传导延迟亚组，分布较为均匀。缺血性和非缺血性心力衰竭患者的分布模式或 LV 不同步程度无差异。
适合 CRT 的心力衰竭患者中，外侧、后侧和下侧节段占总最晚激活节段的 73%。所有 QRS 形态均存在 LV 不同步。最晚激活部位可能在外侧或后侧节段之外，因此超声心动图评估 LV 不同步和最晚激活部位是优化 CRT 后患者预后的一种有价值的技术。
