Aims Mild to moderate functional mitral regurgitation (MR) is common in patients with heart failure and preserved ejection fraction (HFpEF) where it is usually considered as an innocent bystander. We hypothesized that MR in HFpEF reflects greater left atrial (LA) myopathy, leading to more adverse haemodynamics and poorer exercise reserve. Methods and results Patients with HFpEF (n = 280) with and without MR underwent echocardiography, invasive haemodynamic exercise testing, and expired gas analysis. As compared to non‐MR‐HFpEF (n = 163), patients with MR‐HFpEF (n = 117; 78 mild and 39 moderate, central jet in 90%) were older, more likely female, with lower body mass and higher prevalence of atrial fibrillation (AF). HFpEF patients with MR displayed greater LA volume, reduced LA strain and compliance, and greater mitral annular dilatation, which was strongly correlated with LA dilatation (r = 0.63, P < 0.0001) but was only weakly related to left ventricular remodelling (r = 0.37). Patients with MR‐HFpEF displayed worse biventricular function, more adverse pulmonary haemodynamics, impaired pulmonary vasodilatation, blunted right ventricular reserve, and reduced cardiac output with exercise as compared to non‐MR‐HFpEF. Importantly, these findings were maintained after excluding patients with HFpEF and AF, suggesting a role for LA myopathy in contributing to MR in HFpEF, independent of rhythm. Conclusions Functional MR in patients with HFpEF reflects LA myopathy, even in the absence of AF, and is associated with greater haemodynamic severity of disease and poorer functional capacity. Further study is required to better define causal mechanisms and potential treatments for MR and LA dysfunction in patients with HFpEF.

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Our aims were (i) to compare in vivo measurements of myocardial elasticity by shear wave dispersion ultrasound vibrometry (SDUV) with those by the conventional pressure-segment length method, and (ii) to quantify changes in myocardial viscoelasticity during systole and diastole after reperfused acute myocardial infarction. The shear elastic modulus (μ1) and viscous coefficient (μ2) of left ventricular myocardium were measured by SDUV in 10 pigs. Young’s elastic modulus was independently measured by the pressure-segment length method. Measurements made with the SDUV and pressure-segment length methods were strongly correlated. At reperfusion, μ1 and μ2 in end-diastole were increased. Less consistent changes were found during systole. In all animals, μ1 increased linearly with left ventricular pressure developed during systole. Preliminary results suggest that m1 is preload dependent. This is the first study to validate in vivo measurements of myocardial elasticity by a shear wave method. In this animal model, the alterations in myocardial viscoelasticity after a myocardial infarction were most consistently detected during diastole.

Ultrasound tissue harmonic imaging is widely used to improve ultrasound B-mode imaging quality thanks to its effectiveness in suppressing imaging artifacts associated with ultrasound reverberation, phase aberration, and clutter noise. In ultrasound shear wave elastography (SWE), because the shear wave motion signal is extracted from the ultrasound signal, these noise sources can significantly deteriorate the shear wave motion tracking process and consequently result in noisy and biased shear wave motion detection. This situation is exacerbated in in vivo SWE applications such as heart, liver, and kidney. This paper, therefore, investigated the possibility of implementing harmonic imaging, specifically pulse-inversion harmonic imaging, in shear wave tracking, with the hypothesis that harmonic imaging can improve shear wave motion detection based on the same principles that apply to general harmonic B-mode imaging. We first designed an experiment with a gelatin phantom covered by an excised piece of pork belly and show that harmonic imaging can significantly improve shear wave motion detection by producing less underestimated shear wave motion and more consistent shear wave speed measurements than fundamental imaging. Then, a transthoracic heart experiment on a freshly sacrificed pig showed that harmonic imaging could robustly track the shear wave motion and give consistent shear wave speed measurements while fundamental imaging could not. Finally, an in vivo transthoracic study of seven healthy volunteers showed that the proposed harmonic imaging tracking sequence could provide consistent estimates of the left ventricular myocardium stiffness in end-diastole with a general success rate of 80% and a success rate of 93.3% when excluding the subject with Body Mass Index (BMI) higher than 25. These promising results indicate that pulse-inversion harmonic imaging can significantly improve shear wave motion tracking and thus potentially facilitate more robust assessment of tissue elasticity by SWE.

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