Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON, Canada K1Y 4W7.
Europace. 2012 May;14(5):690-5. doi: 10.1093/europace/eur381. Epub 2011 Dec 14.
Cardiac resynchronization therapy (CRT) benefits patients with heart failure and a wide QRS complex. Still, one-third derive no clinical benefit and a majority of patients demonstrate no objective improvement of left ventricular (LV) function. Left bundle branch block (LBBB) is a strong predictor of response to CRT. We evaluated whether absence of electrocardiogram (ECG) markers of residual left bundle (LB) conduction in guideline-defined LBBB predicted a greater response to CRT.
An r wave ≥1 mm in lead V1 (r-V1) and/or a q wave ≥1 mm in lead aVL (q-aVL) was used to identify patients with residual LB conduction. Forty patients with a wide QRS were prospectively enrolled and subdivided into three groups: complete LBBB (cLBBB), LBBB without r-V1 or q-aVL (n = 12); LBBB with residual LB conduction (rLBBB), LBBB with r-V1 and/or q-aVL (n = 15); and non-specific intraventricular conduction delay (IVCD), (n = 13). Following CRT: mean change in left ventricular ejection fraction was 11.9 ± 11.9% in cLBBB, 3.8 ± 5.4% in rLBBB (P= 0.045), and 2.5 ± 4.4% in IVCD (P= 0.02 cLBBB vs. IVCD); mean reduction in left ventricular end-systolic volume was 26.4 ± 39.2% in cLBBB, 14.3 ± 22.9% in rLBBB (P= 0.35), and 5.6 ± 17.3% in IVCD (P= 0.11 cLBBB vs. IVCD); mean change in native QRS duration was -8.0 ± 11.0 ms in cLBBB, -0.8 ± 8.24 ms in rLBBB (P= 0.07), and 0.15 ± 8.0 ms in IVCD (P= 0.048 cLBBB vs. IVCD).
In patients with guideline-defined LBBB, the absence of ECG markers of residual LB conduction was predictive of a greater improvement in LV function with CRT.
心脏再同步治疗（CRT）可使心力衰竭和宽 QRS 复合物的患者受益。然而，仍有三分之一的患者没有临床获益，大多数患者的左心室（LV）功能没有客观改善。左束支传导阻滞（LBBB）是对 CRT 反应的强烈预测指标。我们评估了指南定义的 LBBB 中是否存在心电图（ECG）残留左束（LB）传导的标志物是否可以预测 CRT 反应更大。
在导联 V1 中 r 波≥1mm（r-V1）和/或在导联 aVL 中 q 波≥1mm（q-aVL）用于识别残留 LB 传导的患者。前瞻性纳入 40 例宽 QRS 患者，并分为三组：完全 LBBB（cLBBB），无 r-V1 或 q-aVL 的 LBBB（n=12）；有残留 LB 传导的 LBBB（rLBBB），有 r-V1 和/或 q-aVL 的 LBBB（n=15）；和非特异性室内传导延迟（IVCD）（n=13）。在 CRT 后：cLBBB 的左心室射血分数的平均变化为 11.9±11.9%，rLBBB 为 3.8±5.4%（P=0.045），IVCD 为 2.5±4.4%（P=0.02 cLBBB 与 IVCD 相比）；cLBBB 的左心室收缩末期容积的平均减少量为 26.4±39.2%，rLBBB 为 14.3±22.9%（P=0.35），IVCD 为 5.6±17.3%（P=0.11 cLBBB 与 IVCD 相比）；cLBBB 的固有 QRS 持续时间的平均变化为-8.0±11.0ms，rLBBB 为-0.8±8.24ms（P=0.07），IVCD 为 0.15±8.0ms（P=0.048 cLBBB 与 IVCD 相比）。
在指南定义的 LBBB 患者中，ECG 残留 LB 传导标志物的缺失可预测 CRT 后 LV 功能的更大改善。
