Li Guangyuan, Wang Yonghuai, Pang Bo, Yang Jun, Ma Chunyan
Department of Cardiovascular Ultrasound, First Hospital of China Medical University, Shenyang, Liaoning, China.
Clinical Medical Research Center of Imaging in Liaoning Province, Shenyang, Liaoning, China.
Cardiovasc Ultrasound. 2025 May 1;23(1):7. doi: 10.1186/s12947-025-00342-6.
Early identification of subclinical left ventricular (LV) systolic dysfunction (LVSD) in patients with isolated left bundle branch block (LBBB) and preserved LV ejection fraction (LVEF), termed LBBB, is clinically important. Electrocardiography (ECG) has been proposed as a potential screening tool for detecting subclinical LVSD in LBBB patients, but its effectiveness has not been fully validated. This study investigated the relationships between specific ECG characteristics and subclinical LVSD in LBBB patients.
The study included 111 patients with LBBB. Two-dimensional speckle-tracking echocardiography was used to derive the LV global longitudinal strain (LV GLS), with LV GLS>-20% indicating subclinical LVSD. The recorded ECG characteristics included heart rate, QRS duration, P-R duration, QRS morphology, T-wave morphology, the presence of QS patterns, and discordant LBBB, among others. The presence of QS patterns was defined as the absence of R-waves in lead V1 (or R-waves < 1 mm with a scale of 10 mm/mV). Discordant LBBB was defined as an inconsistency between the T wave and QRS complex in leads I, V5, and V6.
Among the patients, 52 exhibited subclinical LVSD. Compared with those with normal LV systolic function, patients with subclinical LVSD had longer QRS durations, a higher frequency of QS patterns, and more instances of discordant LBBB. A QRS duration of 153 ms was identified as the optimal cut-off for detecting subclinical LVSD, with a sensitivity of 75.00% and specificity of 72.88%. The combination of QRS duration, the presence of QS patterns, and discordant LBBB produced the highest area under the curve of 0.82. Incorporating the presence of QS patterns and discordant LBBB into the QRS duration model increased the integrated discriminant index from 0.07 to 0.15.
QRS duration, the presence of QS patterns, and discordant LBBB are independent predictors of subclinical LVSD in patients with LBBB. An integrated ECG assessment may offer a straightforward screening method for identifying subclinical LVSD in this population.
在孤立性左束支传导阻滞（LBBB）且左心室射血分数（LVEF）保留的患者中，早期识别亚临床左心室（LV）收缩功能障碍（LVSD）（称为LBBB）具有重要临床意义。心电图（ECG）已被提议作为检测LBBB患者亚临床LVSD的潜在筛查工具，但其有效性尚未得到充分验证。本研究调查了LBBB患者特定心电图特征与亚临床LVSD之间的关系。
该研究纳入了111例LBBB患者。使用二维斑点追踪超声心动图来得出左心室整体纵向应变（LV GLS），LV GLS > -20%表明存在亚临床LVSD。记录的心电图特征包括心率、QRS波时限、P-R间期、QRS波形态、T波形态、QS波型的存在情况以及不一致性LBBB等。QS波型的存在定义为V1导联无R波（或R波<1mm，比例尺为10mm/mV）。不一致性LBBB定义为I、V5和V6导联中T波与QRS波群不一致。
在这些患者中，52例表现出亚临床LVSD。与左心室收缩功能正常的患者相比，亚临床LVSD患者的QRS波时限更长，QS波型出现频率更高，不一致性LBBB的情况更多。QRS波时限153ms被确定为检测亚临床LVSD的最佳截断值，敏感性为75.00%，特异性为72.88%。QRS波时限、QS波型的存在情况和不一致性LBBB的组合产生的曲线下面积最高，为0.82。将QS波型的存在情况和不一致性LBBB纳入QRS波时限模型可使综合判别指数从0.07提高到0.15。
QRS波时限、QS波型的存在情况和不一致性LBBB是LBBB患者亚临床LVSD的独立预测因素。综合心电图评估可能为识别该人群中的亚临床LVSD提供一种简单的筛查方法。
