Myocardial fibrosis and left ventricular (LV) longitudinal strain are independently associated with adverse clinical outcomes. However, the relationship between tissue properties and strain indices as well as their collective impact on outcomes are yet to be fully elucidated. We aim to investigate the relationship between LV global longitudinal strain (GLS), global circumferential strain (GCS) and global radial strain (GRS) with extracellular volume (ECV) and their collective impact. Consecutive patients referred for clinical cardiovascular magnetic resonance (CMR) due to cardiomyopathy were prospectively enrolled. All patients underwent CMR with T1 mapping. ECV was calculated incorporating native and post-contrast T1 as well as hematocrit. LV GLS, GCS, and GRS were assessed by feature tracking. Hazard ratios and Kaplan–Meier curves were produced to assess the association between strains and T1 mapping indices with a composite outcome of all-cause mortality and hospitalized heart failure. The study consisted of 259 patients with mixed referring diagnoses of non-ischemic/ischemic cardiomyopathy and 21 normal controls. Decreased GLS, GCS and GRS were associated with increased ECV, increased native T1, and reduced post-contrast T1 in a dose dependent manner when T1 or ECV was in the abnormal range. After a mean follow-up of 31 ± 23 months, 41 events occurred including 37 heart failure admissions and 4 deaths. Kaplan–Meier plots demonstrated that reduced strains were associated with reduced event-free survival predominantly in patients with increased ECV (≥ 28.3%). The worst outcome was among those with both reduced strains and increased ECV. In the multivariable models, increased ECV, reduced post-contrast T1 and reduced strains in all 3 directions remained predictors of outcome risk, respectively. Our findings highlight the intrinsic link between altered CMR tissue properties and impaired myocardial mechanical performance and additionally demonstrate improved risk stratification by characterizing tissue property among patients with reduced strain.

中文翻译：

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左心室应变减少与细胞外容量增加的关联及其对临床结果的集体影响


心肌纤维化和左心室（LV）纵向应变与不良临床结果独立相关。然而，组织特性和应变指数之间的关系以及它们对结果的集体影响尚未完全阐明。我们的目的是研究左心室整体纵向应变（GLS）、整体周向应变（GCS）和整体径向应变（GRS）与细胞外体积（ECV）之间的关系及其集体影响。因心肌病而转诊进行临床心血管磁共振（CMR）的连续患者被前瞻性纳入。所有患者均接受了 CMR 和 T1 映射。 ECV 的计算结合了原始 T1 和对比后 T1 以及血细胞比容。通过特征跟踪评估 LV GLS、GCS 和 GRS。绘制风险比和 Kaplan-Meier 曲线来评估菌株和 T1 映射指数与全因死亡率和住院心力衰竭综合结果之间的关联。该研究由 259 名混合转介诊断为非缺血性/缺血性心肌病的患者和 21 名正常对照组成。当 T1 或 ECV 处于异常范围时，GLS、GCS 和 GRS 降低与 ECV 升高、天然 T1 升高以及对比后 T1 降低呈剂量依赖性相关。经过平均 31 ± 23 个月的随访后，发生了 41 起事件，其中 37 起因心力衰竭入院，4 起死亡。 Kaplan-Meier 图表明，菌株减少与无事件生存期缩短相关，主要发生在 ECV 增加的患者中 (≥ 28.3%)。最糟糕的结果是那些应变减少但 ECV 增加的患者。 在多变量模型中，ECV 增加、对比后 T1 减少和所有 3 个方向的应变减少仍然分别是结果风险的预测因素。我们的研究结果强调了改变的 CMR 组织特性与受损的心肌机械性能之间的内在联系，并另外证明了通过表征应变减少的患者的组织特性来改善风险分层。