Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
Biostatistics Unit, Mayo Clinic, Jacksonville, Florida.
JACC Heart Fail. 2016 Nov;4(11):897-903. doi: 10.1016/j.jchf.2016.07.002. Epub 2016 Sep 7.
This study aimed to define the prognosis for patients with left bundle branch block (LBBB) and a mildly to moderately reduced left ventricular ejection fraction (LVEF) (36% to 50%) as well as to clarify whether LBBB remained a negative prognostic marker in this group.
LBBB is associated with worse outcomes in patients with heart failure in the setting of severely reduced LVEF. The level of morbidity and mortality associated with LBBB in the setting of a mildly to moderately reduced LVEF (36% to 50%) has not been clearly characterized. This knowledge is important to clarify the potential benefit of cardiac resynchronization therapy in this group.
All patients identified as having an LBBB from 1994 to 2014 were included in the study if they had a baseline echocardiogram within 1 year and an LVEF between 36% and 50%. A control group without intraventricular conduction abnormality matched on age, sex, baseline LVEF, and date of echocardiogram was created. Outcomes were compared between the 2 groups.
Of 1,436 patients meeting inclusion criteria, 54% were male. Mean age was 67 ± 13 years, and mean LVEF at baseline was 44 ± 4%. There was no difference in baseline heart failure diagnosis between groups. There were significantly higher rates of baseline coronary artery disease in the control group and higher rates of aortic stenosis in the LBBB group. LBBB was associated with significantly worse mortality (hazard ratio [HR]: 1.17; 95% confidence interval [CI]: 1.00 to 1.36), an LVEF drop to 35% or less (HR: 1.34; 95% CI: 1.09 to 1.63), and the need for an implantable cardioverter-defibrillator (HR: 1.50; 95% CI: 1.10 to 2.10). Mortality remained significantly higher in the LBBB group when controlled for heart failure, coronary artery disease, and aortic stenosis (p = 0.04).
Patients with a mildly to moderately reduced LVEF and LBBB have poor clinical outcomes that are significantly worse than those for patients without conduction system disease. This group may obtain benefit from cardiac resynchronization therapy and deserves to be studied in prospective trials.
本研究旨在定义左束支传导阻滞（LBBB）和轻度至中度左心室射血分数（LVEF）降低（36%至 50%）患者的预后，并阐明 LBBB 在该组患者中是否仍然是一个负面预后标志物。
在严重 LVEF 降低的心力衰竭患者中，LBBB 与更差的结局相关。在轻度至中度 LVEF（36%至 50%）降低的情况下，与 LBBB 相关的发病率和死亡率水平尚不清楚。了解这一点对于阐明该组患者心脏再同步治疗的潜在获益非常重要。
从 1994 年至 2014 年期间，所有被诊断为 LBBB 的患者，如果在 1 年内进行基线超声心动图检查且 LVEF 在 36%至 50%之间，则纳入本研究。创建了一个无室内传导异常且年龄、性别、基线 LVEF 和超声心动图日期匹配的对照组。比较两组患者的预后。
符合纳入标准的 1436 例患者中，54%为男性。平均年龄为 67±13 岁，基线 LVEF 为 44±4%。两组之间的基线心力衰竭诊断无差异。对照组的基线冠状动脉疾病发生率较高，而 LBBB 组的主动脉瓣狭窄发生率较高。LBBB 与死亡率显著升高（风险比[HR]：1.17；95%置信区间[CI]：1.00 至 1.36）、LVEF 降至 35%或更低（HR：1.34；95% CI：1.09 至 1.63）和需要植入式心脏复律除颤器（HR：1.50；95% CI：1.10 至 2.10）相关。在控制心力衰竭、冠状动脉疾病和主动脉瓣狭窄后，LBBB 组的死亡率仍显著升高（p=0.04）。
轻度至中度 LVEF 降低且存在 LBBB 的患者临床结局较差，明显差于无传导系统疾病患者。该组患者可能受益于心脏再同步治疗，值得在前瞻性试验中进行研究。
