Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN 55455, United States of America.
Minneapolis Heart Institute East, Allina Health, St Paul, MN 55102, United States of America; Heart Rhythm Science Center, Minneapolis Heart Institute Foundation, Minneapolis, MN 55407, United States of America.
J Electrocardiol. 2022 May-Jun;72:72-78. doi: 10.1016/j.jelectrocard.2022.03.006. Epub 2022 Mar 20.
Cardiac resynchronization therapy (CRT) response is proportional to QRS duration (QRS). We hypothesize that this is, in part, due to slower conduction velocity and hence wider range of programmed device settings that produce adequate electrical wavefront fusion and resynchronization in wider QRS patients.
CRT patients (n = 122) with left ventricular (LV) conduction delay, sinus rhythm and intact atrioventricular node conduction were studied. Patients were categorized by QRS: narrow (<120 ms; n = 20); moderate (120-150 ms, n = 37); and prolonged (≥150 ms; n = 65). Electrocardiographic data was acquired during native rhythm and LV-only pacing at varying atrioventricular delays (AVDs). Electrical synchrony was quantified as cardiac resynchronization index (CRI) using multi‑lead electrocardiographic systems and a proprietary algorithm that quantified wavefront fusion. A Gaussian distribution equation was fitted to CRI response.
Peak CRI was high (87.6 ± 6.3%) and similar (p = 0.716) across QRS groups. The standard deviation of the Gaussian distribution significantly correlated with QRS (R = 0.614, p < 0.001), and progressively and significantly (p < 0.001) increased as QRS increased from narrow (34.8 ± 10.0 ms), to moderate (50.6 ± 8.4 ms), to prolonged (67.6 ± 18.3 ms). At AVDs 20 and 40 ms from optimal, CRI differed significantly (p < 0.001) between groups, with progressively higher CRI values as native QRS increased.
Electrical resynchronization with optimally programmed LV-only pacing was similar between patients with varying QRS, including patients with narrow QRS. The resynchronization window that corresponded with optimal electrical resynchronization decreased as native QRS decreased. This finding provides one potential explanation for the lack of significant benefit of CRT in narrow QRS patients in previous studies.
心脏再同步治疗（CRT）的反应与 QRS 时限（QRS）成正比。我们假设，这在一定程度上是由于传导速度较慢，因此在更宽 QRS 患者中，需要更广泛的程控设备设置范围，才能产生足够的电前向融合和再同步。
研究了 122 例左心室（LV）传导延迟、窦性节律和房室结传导正常的 CRT 患者。根据 QRS 分为 3 组：窄（<120ms；n=20）；中（120-150ms，n=37）；宽（≥150ms；n=65）。在固有节律和 LV 仅起搏时，在不同的房室延迟（AVD）下获取心电图数据。使用多导联心电图系统和一种量化前向融合的专有算法，量化电同步性，作为心脏再同步指数（CRI）。使用高斯分布方程拟合 CRI 反应。
峰值 CRI 较高（87.6±6.3%），且在 QRS 组之间相似（p=0.716）。高斯分布的标准差与 QRS 显著相关（R=0.614，p<0.001），随着 QRS 从窄（34.8±10.0ms）到中（50.6±8.4ms）再到宽（67.6±18.3ms），逐渐显著增加（p<0.001）。在优化 AVD 分别为 20ms 和 40ms 时，各组间 CRI 差异显著（p<0.001），随着固有 QRS 的增加，CRI 值逐渐升高。
在不同 QRS 的患者中，包括 QRS 正常的患者，优化的 LV 仅起搏的电再同步相似。与最佳电再同步相对应的再同步窗口随着固有 QRS 的减少而减小。这一发现为以前研究中窄 QRS 患者 CRT 获益不显著提供了一个潜在的解释。
