Institute of Clinical Medicine, University of Eastern Finland, Joensuu, Finland.
Department of Nuclear Medicine and Clinical Physiology, Kuopio University Hospital, PL 100, 70029 KYS, Kuopio, Finland.
J Nucl Cardiol. 2021 Jun;28(3):1140-1150. doi: 10.1007/s12350-020-02054-y. Epub 2020 Feb 14.
To better understand the mechanisms of left ventricular (LV) mechanical dyssynchrony (LVMD), we explored the relative contributions of QRS duration (QRSd), LV ejection fraction (EF), volumes and scar to LVMD measured by gated single-photon emission tomography in a population of consecutive patients with left bundle branch block (LBBB) and right bundle branch block (RBBB) compared to controls.
Myocardial perfusion imaging studies of 275 LBBB and 83 RBBB patients from three centers were analyzed. LVMD was defined as an abnormal phase bandwidth or phase standard deviation. Hospital and gender-specific normal values were obtained from 172 controls.
The prevalence of LVMD was 85 and 40% in LBBB and RBBB, respectively. Ejection fraction, scar severity, and LBBB morphology independently explained 70% of variance seen in PhaseBW. Ejection fraction had the highest area under the curve (AUC 0.918) in the receiver operating characteristics analysis of LVMD with an optimal cut-off of 47% (sensitivity 73% and specificity 98%). Notably, QRSd was not predictive.
LV mechanical dysfunction plays a greater role than conduction abnormality in the genesis of LVMD, a finding that is intriguing in the context of contemporary literature which suggests that QRSd is the parameter that is most predictive of CRT response.
为了更好地理解左心室（LV）机械不同步（LVMD）的机制，我们研究了连续左束支传导阻滞（LBBB）和右束支传导阻滞（RBBB）患者与对照组相比，QRS 持续时间（QRSd）、LV 射血分数（EF）、容积和瘢痕对门控单光子发射断层扫描测量的 LVMD 的相对贡献。
对来自三个中心的 275 例 LBBB 和 83 例 RBBB 患者的心肌灌注成像研究进行了分析。LVMD 定义为异常相位带宽或相位标准差。从 172 名对照中获得了医院和性别特异性的正常值。
LBBB 和 RBBB 患者的 LVMD 患病率分别为 85%和 40%。EF、瘢痕严重程度和 LBBB 形态独立解释了相位 BW 中观察到的 70%的变异性。EF 在 LVMD 的受试者工作特征分析中具有最高的曲线下面积（AUC 0.918），最佳截断值为 47%（敏感性 73%，特异性 98%）。值得注意的是，QRSd 没有预测作用。
LV 机械功能障碍在 LVMD 的发生中比传导异常起更大的作用，这一发现在当代文献中令人感到好奇，这些文献表明 QRSd 是最能预测 CRT 反应的参数。
