Department of Cardiology, Royal Papworth Hospital, Cambridge, United Kingdom.
Division of Cardiology, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Am J Cardiol. 2018 Nov 15;122(10):1754-1760. doi: 10.1016/j.amjcard.2018.08.008. Epub 2018 Aug 21.
It is unknown whether the presence of a sarcomeric mutation alone is sufficient to result in abnormal myocardial force generation, or whether additional changes in myocardial architecture (hypertrophy, disarray, and fibrosis) are required to impair systolic function. Speckle tracking echocardiography allows quantification of global strain/strain rates, twist, and dyssynchrony. In the present study we sought to further elucidate early abnormalities of myocardial mechanics in sarcomeric mutation carriers without evidence of clinical disease. Sixty genotype-positive left ventricular hypertrophy-negative (G+left ventricular hypertrophy [LVH]-) patients and 60 normal controls were studied. Velocity vector imaging was applied retrospectively to echocardiographic images to quantify global longitudinal and circumferential strain/strain rate, and rotation parameters. The G+LVH- group demonstrated both smaller left ventricular diastolic cavity dimensions (4.5 ± 0.6 cm vs 4.8 ± 0.4 cm) and a higher LVEF (66 ± 6% vs 60 ± 5%) compared with controls. An increase in circumferential subendocardial systolic strain (-30 ± 5 vs -27 ± 3%) and both systolic and diastolic subendocardial strain rate was seen in the G+LVH- group. Peak rotation angles were higher at the base and apex, with an increase in total twist (9.0 ± 3.8 vs 6.9 ± 2.9). In the control group, global and average segmental strain were similar, suggesting no/minimal dyssynchrony (global mechanical synchrony index [GMSi] 0.97-0.98). In the G+LVH- group GMSi was significantly lower (subendocardial GMSi 0.95; subepicardial GMSi 0.60), suggesting increasing subendocardial to subepicardial dyssynchrony. In conclusion, utilizing multilayer strain analysis, we demonstrate that G+LVH- subjects have enhanced subendocardial systolic strain rate and twist, as well as mechanical dyssynchrony within the left ventricular myocardium. These results demonstrate that abnormalities in myocardial mechanics precede the development of clinical hypertrophy.
目前尚不清楚肌节突变的存在是否足以导致心肌收缩力产生异常，或者是否需要心肌结构（肥大、紊乱和纤维化）的其他变化来损害收缩功能。斑点追踪超声心动图可定量评估整体应变/应变速率、扭转和不同步。本研究旨在进一步阐明无临床疾病证据的肌节突变携带者的心肌力学早期异常。研究纳入 60 名基因型阳性左心室肥厚阴性（G+左心室肥厚[LVH]-）患者和 60 名正常对照者。应用速度向量成像对超声心动图图像进行回顾性分析，以定量评估整体纵向和圆周应变/应变速率及旋转参数。G+LVH-组的左心室舒张腔尺寸（4.5±0.6cm 比 4.8±0.4cm）和 LVEF（66±6%比 60±5%）均低于对照组。G+LVH-组的收缩期心内膜下圆周应变增加（-30±5%比-27±3%），收缩期和舒张期心内膜下应变速率均增加。基底和心尖的峰值旋转角度更高，总扭转增加（9.0±3.8 比 6.9±2.9）。在对照组中，整体和平均节段应变相似，提示无/最小不同步（整体机械同步指数[GMSi]0.97-0.98）。G+LVH-组的 GMSi 显著降低（心内膜下 GMSi 0.95；心外膜下 GMSi 0.60），提示心内膜下到心外膜下的不同步增加。总之，利用多层应变分析，我们发现 G+LVH-患者的左心室心肌心内膜下收缩期应变率和扭转增加，以及心肌力学不同步。这些结果表明，心肌力学异常先于临床肥厚的发展。
