BACKGROUND Left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT) has shown encouraging results for QRS duration reduction and heart function improvement. However, the feasibility and efficacy of LOT-CRT have not been well established in intraventricular conduction delay patients. This study aims to assess and compare the efficacy and clinical outcome of CRT based on left bundle branch pacing, combined with coronary sinus left ventricular pacing (LOT-CRT) with CRT via biventricular pacing (BiV-CRT) in intraventricular conduction delay patients indicated for CRT. METHODS Consecutive patients with intraventricular conduction delay and CRT indications were assigned nonrandomized to LOT-CRT (n=30) or BiV-CRT (n=55). Addition of the left bundle branch pacing (or coronary venous) lead was at the discretion of the implanting physician guided by suboptimal paced QRS complex and on clinical grounds. Echocardiographic parameters and clinical characteristics were accessed at baseline and during 2-years' follow-up. RESULTS Success rate for LOT-CRT and BiV-CRT was 96.8% and 96.4%. LOT-CRT had greater reduction of QRS duration compared with BiV-CRT (42.7±17.4 ms versus 21.9±21.5 ms; P<0.001). Higher left ventricular ejection fraction was also achieved in LOT-CRT than BiV-CRT at 6-month (36.7±9.8% versus 30.5±6.4%; P<0.05), 12-month (34.8±7.6% versus 30.3±6.2%; P<0.05), 18-month (36.3±7.9% versus 28.1±6.6%; P<0.005), and 24-month follow-up (37±9.5% versus 30.5±7%; P<0.05). Adverse clinical outcomes including heart failure rehospitalization and mortality were lower in LOT-CRT group for 24 months follow-up (hazard ratio, 0.33; P=0.035). CONCLUSIONS LOT-CRT improves ventricular electrical synchrony and may provide greater clinical outcomes as compared with BiV-CRT in intraventricular conduction delay patients. These findings need further evaluation in future randomized controlled trials.

中文翻译：

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应用左束支起搏优化心脏再同步治疗的心室内传导延迟患者长期随访期间的电再同步和临床结果。

背景左束支优化心脏再同步治疗（LOT-CRT）在减少 QRS 时限和改善心功能方面显示出令人鼓舞的结果。然而，LOT-CRT 在心室内传导延迟患者中的可行性和有效性尚未得到很好的证实。本研究旨在评估和比较基于左束支起搏的 CRT 联合冠状窦左心室起搏 (LOT-CRT) 与双心室起搏 CRT (BiV-CRT) 对于心室内传导延迟患者的疗效和临床结果显像管。方法连续存在心室内传导延迟和 CRT 指征的患者被非随机分配至 LOT-CRT (n=30) 或 BiV-CRT (n=55)。添加左束支起搏（或冠状静脉）导线由植入医师在次优起搏 QRS 波群指导下并根据临床情况酌情决定。在基线和 2 年随访期间获取超声心动图参数和临床特征。结果 LOT-CRT 和 BiV-CRT 的成功率分别为 96.8% 和 96.4%。与 BiV-CRT 相比，LOT-CRT 的 QRS 时限缩短幅度更大（42.7±17.4 ms 与 21.9±21.5 ms；P<0.001）。LOT-CRT 的左心室射血分数在 6 个月时也比 BiV-CRT 更高（36.7±9.8% 对比 30.5±6.4%；P<0.05）、12 个月（34.8±7.6% 对比 30.3±6.2%；P<0.05）。 P<0.05）、18 个月（36.3±7.9% 对比 28.1±6.6%；P<0.005）和 24 个月随访（37±9.5% 对比 30.5±7%；P<0.05）。在 24 个月的随访中，LOT-CRT 组的不良临床结局（包括心力衰竭再住院和死亡率）较低（风险比为 0.33；P=0.035）。结论 LOT-CRT 可以改善心室电同步，并且与 BiV-CRT 相比，可以为心室内传导延迟患者提供更好的临床结果。这些发现需要在未来的随机对照试验中进一步评估。