Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Circ Heart Fail. 2013 Nov;6(6):1190-8. doi: 10.1161/CIRCHEARTFAILURE.113.000380. Epub 2013 Aug 30.
The impact of QRS morphology and duration on the effectiveness of cardiac resynchronization therapy (CRT) has been usually assessed separately. The interaction between these 2 simple ECG parameters and their effect on CRT has not been systematically assessed in a large-scale clinical trial.
The Resynchronization-Defibrillation for Ambulatory Heart Failure Trial showed that implantable cardioverter defibrillator-CRT was associated with a significant reduction in the primary end point of all-cause mortality or heart failure hospitalization. For this substudy, we excluded patients in atrial fibrillation and those with a previous pacemaker. All baseline ECGs were reviewed by a panel of 3 experienced electrocardiographers. A total of 1483 patients were included in this study. Of these, 1175 had left bundle-branch block (LBBB) and 308 had non-LBBB. In patients with LBBB receiving implantable cardioverter defibrillator-CRT, there was a reduction in the primary outcome and in each individual component of the primary outcome. Furthermore, there was continuous relationship between QRS duration and extent of benefit. In patients with non-LBBB and QRS ≥160 ms, the hazard ratio for the primary outcome was 0.52 (0.29-0.96; P=0.033); in patients with QRS <160 ms, the hazard ratio was 1.38 (0.88-2.14; P=0.155).
In patients with LBBB, there was a continuous relationship between broader QRS and greater benefit from implantable cardioverter defibrillator-CRT. However, our data do not support the use of implantable cardioverter defibrillator-CRT in patients with non-LBBB, especially when the QRS duration is <160 ms. There may be some delayed benefit when the QRS is ≥160 ms, but this needs further investigation.
URL: http://www.clinicaltrials.gov. Unique identifier: NCT00251251.
QRS 形态和持续时间对心脏再同步治疗（CRT）效果的影响通常是分开评估的。这两个简单的心电图参数之间的相互作用及其对 CRT 的影响尚未在大规模临床试验中系统评估。
心脏再同步除颤治疗心力衰竭试验表明，植入式心脏复律除颤器-CRT 与全因死亡率或心力衰竭住院的主要终点显著降低相关。对于这项亚研究，我们排除了心房颤动患者和那些有先前起搏器的患者。所有基线心电图均由一个由 3 名经验丰富的心电图专家组成的小组进行审查。共有 1483 名患者纳入本研究。其中，1175 名患者有左束支传导阻滞（LBBB），308 名患者无 LBBB。在接受植入式心脏复律除颤器-CRT 的 LBBB 患者中，主要终点和主要终点的各个组成部分均有降低。此外，QRS 持续时间与获益程度之间存在连续关系。在 QRS ≥160ms 的非 LBBB 患者中，主要结局的危险比为 0.52（0.29-0.96；P=0.033）；在 QRS<160ms 的患者中，危险比为 1.38（0.88-2.14；P=0.155）。
在 LBBB 患者中，更广泛的 QRS 与植入式心脏复律除颤器-CRT 更大获益之间存在连续关系。然而，我们的数据不支持在非 LBBB 患者中使用植入式心脏复律除颤器-CRT，特别是当 QRS 持续时间<160ms 时。当 QRS 为≥160ms 时可能会有一些延迟获益，但这需要进一步研究。
