Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States; Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
Int J Cardiol. 2019 Jan 1;274:208-213. doi: 10.1016/j.ijcard.2018.07.057. Epub 2018 Jul 11.
Indices of cardiac mechanics are sensitive markers of subclinical myocardial dysfunction. Improved understanding of the clinical correlates and heritability of cardiac mechanics could result in novel insight into the acquired and genetic risk factors for myocardial dysfunction. Therefore, we sought to determine the clinical correlates and heritability of indices of cardiac mechanics in whites and African Americans (AAs).
We examined 2058 participants stratified by race (1104 whites, 954 AA) in the Hypertension Genetic Epidemiology Network (HyperGEN), a population- and family-based study, and performed digitization of analog echocardiograms with subsequent speckle-tracking analysis. We used linear mixed effects models to determine the clinical correlates of indices of cardiac mechanics (longitudinal, circumferential, radial strain; early diastolic strain rate; and early diastolic tissue velocities). Heritability estimates for cardiac mechanics were calculated using maximum-likelihood variance component analyses in Sequential Oligogenic Linkage Analysis Routine (SOLAR), with adjustment for clinical and echocardiographic covariates.
Several clinical characteristics and conventional echocardiographic parameters were found to be associated with speckle-tracking traits of cardiac mechanics. Male sex, blood pressure, and fasting glucose were associated with worse longitudinal strain (LS) (P < 0.05 for all) after multivariable adjustment. After adjustment for covariates, LS, e' velocity, and early diastolic strain rate were found to be heritable; LS and e' velocity had higher heritability estimates in AAs compared to whites.
Indices of cardiac mechanics are heritable traits even after adjustment for clinical and conventional echocardiographic correlates. These findings provide the basis for future studies of genetic determinants of these traits that may elucidate race-based differences in heart failure development.
心脏力学指标是亚临床心肌功能障碍的敏感标志物。深入了解心脏力学的临床相关性和遗传性，可能为获得性和遗传性心肌功能障碍的危险因素提供新的认识。因此，我们试图确定白人和非裔美国人（AA）心脏力学指标的临床相关性和遗传性。
我们在高血压遗传流行病学网络（HyperGEN）中对 2058 名参与者进行了种族分层（1104 名白人，954 名 AA），这是一项基于人群和家庭的研究，并对模拟超声心动图进行了数字化处理，随后进行斑点追踪分析。我们使用线性混合效应模型来确定心脏力学指标（纵向、圆周、径向应变；舒张早期应变率；舒张早期组织速度）的临床相关性。使用 SOLAR 中的最大似然方差分量分析计算心脏力学的遗传估计值，并对临床和超声心动图协变量进行调整。
几项临床特征和传统超声心动图参数与斑点追踪心脏力学特征相关。多变量调整后，男性、血压和空腹血糖与纵向应变（LS）较差相关（均 P < 0.05）。调整协变量后，LS、e'速度和舒张早期应变率具有遗传性；与白人相比，AA 中的 LS 和 e'速度具有更高的遗传性估计值。
即使在调整了临床和传统超声心动图相关性后，心脏力学指标也是可遗传的特征。这些发现为研究这些特征的遗传决定因素提供了基础，这些决定因素可能阐明心力衰竭发展中的种族差异。
