University Medical Center Utrecht, Utrecht, The Netherlands.
CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, Maastricht, The Netherlands.
J Am Soc Echocardiogr. 2017 Oct;30(10):1012-1020.e2. doi: 10.1016/j.echo.2017.06.004. Epub 2017 Aug 8.
Pronounced echocardiographically measured mechanical dyssynchrony is a positive predictor of response to cardiac resynchronization therapy (CRT), whereas right ventricular (RV) dysfunction is a negative predictor. The aim of this study was to investigate how RV dysfunction influences the association between mechanical dyssynchrony and left ventricular (LV) volumetric remodeling following CRT.
One hundred twenty-two CRT candidates (mean LV ejection fraction, 19 ± 6%; mean QRS width, 168 ± 21 msec) were prospectively enrolled and underwent echocardiography before and 6 months after CRT. Volumetric remodeling was defined as percentage reduction in LV end-systolic volume. RV dysfunction was defined as RV fractional area change < 35%. Mechanical dyssynchrony was assessed as time to peak strain between the septum and LV lateral wall, interventricular mechanical delay, and septal systolic rebound stretch. Simulations of heart failure with an LV conduction delay in the CircAdapt computer model were used to investigate how LV and RV myocardial contractility influence LV dyssynchrony and acute CRT response.
In the entire patient cohort, higher baseline septal systolic rebound stretch, time to peak strain between the septum and LV lateral wall, and interventricular mechanical delay were all associated with LV volumetric remodeling in univariate analysis (R = 0.599, R = 0.421, and R = 0.410, respectively, P < .01 for all). The association between septal systolic rebound stretch and LV volumetric remodeling was even stronger in patients without RV dysfunction (R = 0.648, P < .01). However, none of the mechanical dyssynchrony parameters were associated with LV remodeling in the RV dysfunction subgroup. The computer simulations showed that low RV contractility reduced CRT response but hardly affected mechanical dyssynchrony. In contrast, LV contractility changes had congruent effects on mechanical dyssynchrony and CRT response.
Mechanical dyssynchrony parameters do not reflect the negative impact of reduced RV contractility on CRT response. Echocardiographic prediction of CRT response should therefore include parameters of mechanical dyssynchrony and RV function.
超声心动图测量的机械不同步明显是心脏再同步治疗（CRT）反应的阳性预测因子，而右心室（RV）功能障碍是阴性预测因子。本研究旨在探讨 RV 功能障碍如何影响 CRT 后机械不同步与左心室（LV）容积重构之间的关系。
前瞻性纳入 122 名 CRT 候选者（平均 LV 射血分数为 19±6%；平均 QRS 宽度为 168±21ms），并在 CRT 前和 6 个月后进行超声心动图检查。容积重构定义为 LV 收缩末期容积的百分比减少。RV 功能障碍定义为 RV 节段面积变化<35%。通过测量室间隔与 LV 外侧壁之间的应变峰值时间、室间机械延迟和室间隔收缩期反弹伸展来评估机械不同步。使用 CircAdapt 计算机模型模拟 LV 传导延迟的心力衰竭，以研究 LV 和 RV 心肌收缩力如何影响 LV 不同步和急性 CRT 反应。
在整个患者队列中，较高的基线室间隔收缩期反弹伸展、室间隔与 LV 外侧壁之间的应变峰值时间和室间机械延迟在单因素分析中均与 LV 容积重构相关（R=0.599、R=0.421 和 R=0.410，均 P<0.01）。在无 RV 功能障碍的患者中，室间隔收缩期反弹伸展与 LV 容积重构之间的相关性更强（R=0.648，P<0.01）。然而，在 RV 功能障碍亚组中，机械不同步参数均与 LV 重构无关。计算机模拟显示，RV 收缩力降低会降低 CRT 反应，但几乎不会影响机械不同步。相比之下，LV 收缩力变化对机械不同步和 CRT 反应具有一致的影响。
机械不同步参数不能反映 RV 收缩力降低对 CRT 反应的负面影响。因此，CRT 反应的超声心动图预测应包括机械不同步和 RV 功能的参数。
