Williams Lynne K, Forero Julian F, Popovic Zoran B, Phelan Dermot, Delgado Diego, Rakowski Harry, Wintersperger Bernd J, Thavendiranathan Paaladinesh
Division of Cardiology, Peter Munk Cardiac Center, Ted Rogers Program in Cardiotoxicity Prevention, Toronto General Hospital, University Health Network, 200 Elizabeth Street, Toronto, ON, M5G 2C4, Canada.
Department of Cardiology, Papworth Hospital NHS Foundation Trust, Cambridge, UK.
J Cardiovasc Magn Reson. 2017 Aug 7;19(1):61. doi: 10.1186/s12968-017-0376-0.
Regional variability of longitudinal strain (LS) has been previously described with echocardiography in patients with cardiac amyloidosis (CA), however, the reason for this variability is not completely evident. We sought to describe regional patterns in LS using feature-tracking software applied to cardiovascular magnetic resonance (CMR) cine images in patients with CA, hypertrophic cardiomyopathy (HCM), and Anderson-Fabry's disease (AFD) and to relate these patterns to the distribution of late gadolinium enhancement (LGE).
Patients with CA (n = 45) were compared to LV mass indexed matched patients with HCM (n = 19) and AFD (n = 19). Peak systolic LS measurements were obtained using Velocity Vector Imaging (VVI) software on CMR cine images. A relative regional LS ratio (RRSR) was calculated as the ratio of the average of the apical segmental LS divided by the sum of the average basal and mid-ventricular segmental LS. LGE was quantified for the basal, mid, and apical segments using a threshold of 5SD above remote myocardium. A regional LGE ratio was calculated similar to RRSR.
Patients with CA had significantly had worse global LS (-15.7 ± 4.6%) than those with HCM (-18.0 ± 4.6%, p = 0.046) and AFD (-21.9 ± 5.1%, p < 0.001). The RRSR was higher in patients with CA (1.00 ± 0.31) than in AFD (0.79 ± 0.24; p = 0.018) but not HCM (0.84 ± 0.32; p = 0.114). In CA, a regional difference in LGE burden was noted, with lower LGE in the apex (31.5 ± 19.1%) compared to the mid (38.2 ± 19.0%) and basal (53.7 ± 22.7%; p < 0.001 for both) segments. The regional LGE ratio was not significantly different between patients with CA (0.33 ± 0.15) and AFD (0.47 ± 0.58; p = 0.14) but lower compared to those with HCM (0.72 ± 0.43; p < 0.0001). LGE percentage showed a significant impact on LS (p < 0.0001), with a 0.9% decrease in absolute LS for every 10% increase in LGE percentage.
The presence of marked "relative apical sparing" of LS along with a significant reduction in global LS seen in patients with CA on CMR cine analysis may provide an additional tool to differentiate CA from other cause of LVH. The concomitant presence of a base to apex gradient in quantitative LGE burden suggests that the regional strain gradient may be at least partially explained by the burden of amyloid deposition and fibrosis.
先前已通过超声心动图描述了心脏淀粉样变性（CA）患者纵向应变（LS）的区域变异性，然而，这种变异性的原因尚不完全清楚。我们试图使用特征跟踪软件应用于CA、肥厚型心肌病（HCM）和安德森-法布里病（AFD）患者的心血管磁共振（CMR）电影图像来描述LS的区域模式，并将这些模式与延迟钆增强（LGE）的分布相关联。
将CA患者（n = 45）与左心室质量指数匹配的HCM患者（n = 19）和AFD患者（n = 19）进行比较。使用CMR电影图像上的速度向量成像（VVI）软件获得收缩期峰值LS测量值。计算相对区域LS比值（RRSR），即心尖节段LS平均值除以基底和心室中段节段LS平均值之和的比值。使用比远隔心肌高5个标准差的阈值对基底、中段和心尖节段的LGE进行定量。计算与RRSR类似的区域LGE比值。
CA患者的整体LS（-15.7 ± 4.6%）显著低于HCM患者（-18.0 ± 4.6%，p = 0.046）和AFD患者（-21.9 ± 5.1%，p < 0.001）。CA患者的RRSR（1.00 ± 0.31）高于AFD患者（0.79 ± 0.24；p = 0.018），但与HCM患者（0.84 ± 0.32；p = 0.114）无差异。在CA患者中，观察到LGE负荷的区域差异，心尖部的LGE（31.5 ± 19.1%）低于中段（38.2 ± 19.0%）和基底段（53.7 ± 22.7%；两者p均< 0.001）。CA患者（0.33 ± 0.15）和AFD患者（0.47 ± 0.58；p = 0.14）之间的区域LGE比值无显著差异，但低于HCM患者（0.72 ± 0.43；p < 0.0001）。LGE百分比对LS有显著影响（p < 0.0001），LGE百分比每增加10%，绝对LS降低0.9%。
CMR电影分析显示，CA患者存在明显的LS“相对心尖保留”以及整体LS显著降低，这可能为鉴别CA与其他左心室肥厚原因提供了一种额外工具。定量LGE负荷中从基底到心尖的梯度同时存在表明，区域应变梯度可能至少部分由淀粉样蛋白沉积和纤维化的负荷所解释。
