Our data suggest that cardiac remodeling associated with HCM determines a significant release of miRNAs into the bloodstream: the circulating levels of both cardiac- and non-cardiac-specific miRNAs are significantly increased in the plasma of HCM patients. However, correlation with left ventricular hypertrophy parameters holds true for only a few miRNAs (i.e., miR-199a-5p, -27a, and -29a), whereas only miR-29a is significantly associated with both hypertrophy and fibrosis, identifying it as a potential biomarker for myocardial remodeling assessment in HCM.
Assessment of left ventricular (LV) systolic function is the cornerstone of the echocardiographic examination. There are many echocardiographic parameters that can be used for clinical and research purposes, each one with its pros and cons. The LV ejection fraction is the most used one due to its feasibility and predictability, but it also has many limits, related to both the imaging technique used for calculation and to the definition itself. LV longitudinal function is expression of subendocardial fibers contraction. Because the subendocardium is often involved early in many pathological processes, its analysis has been a fertile field for the development of sensitive parameters. Longitudinal function can be evaluated in many ways, such as M-mode echocardiography, tissue Doppler imaging, and speckle tracking echocardiography. This latter is a relatively new tool to assess LV function through measurement of myocardial strain, with a high temporal and spatial resolution and a better inter- and intra-observer reproducibility compared to Doppler strain. It is angle independent, not affected by translation cardiac movements, and can assess simultaneously the entire myocardium along all the three-dimensional geometrical (longitudinal, circumferential, and radial) axes. Speckle tracking echocardiography also allows the analysis of LV torsion. The aim of this paper was to review the main echocardiographic parameters of LV systolic function and to describe its pros and cons.
Our data support the hypothesis that, in a selected population of patients with ESRD undergoing haemodialysis, myocardial fibrosis is associated with LV diastolic myocardial properties.
Purpose
Hypertrophic cardiomyopathy (HCM) is associated with altered hemodynamics in the left ventricular out flow tract (LVOT) and myocardial tissue abnormalities such as fibrosis. The aim of this study was to quantify changes in LVOT 3D hemodynamics and myocardial extracellular volume fraction (ECV, measure of fibrosis) and to investigate relationships between elevated flow metrics and left ventricular (LV) tissue abnormalities.
Methods and Results
Cardiac MRI including 4D flow (field strength=1.5T, resolution=2.1–4.0×2.1–4.0×2.5–3.2mm3; venc=150–250cm/s; TE/TR/FA=2.2–2.5ms/4.6–4.9ms/15°) for the in-vivo assessment of 3D blood flow velocities with full coverage of the LVOT was applied in 35 patients with HCM (54±15 years) and 10 age matched healthy controls (45±14 years). In addition, pre- and post-contrast myocardial T1-mapping (resolution=2.3×1.8mm, slice thickness=8mm, TE/TR-FA=1.0–1.1ms/2.0–2.2ms/35°) of the LV (basal, mid-ventricular, apical short axis) was performed in a subgroup of 23 HCM patients. Analysis included the segmentation of the LVOT and quantification of peak systolic LVOT pressure gradients and rate of viscous energy loss
EL' as well as left ventricular ECV.
Results
HCM patients demonstrated significantly elevated peak systolic LVOT pressure gradients (21±16mmHg vs. 9±2mmHg) and energy loss
EL' (3.8±2.5mW vs. 1.5±0.7mW, P<0.005) compared to controls. There was a significant relationship between increased LV fibrosis (ECV) with both elevated pressure gradients (R2=0.44, P<0.001) and energy loss
EL' (R2=0.46, P<0.001).
Conclusions
The integration of 4D-flow and T1-mapping-MRI allowed for the evaluation of tissue and flow abnormalities in HCM patients. Our findings suggest a mechanistic link between abnormal LVOT flow, increased LV loading, and adverse myocardial remodeling in HCM.
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