Normal left ventricular mechanics by two-dimensional speckle-tracking echocardiography. Reference values in healthy adults

Relations between aortic stiffness and left ventricular structure and function in older participants in the Age, Gene/Environment Susceptibility--Reykjavik Study

BACKGROUND

Left ventricular (LV) contraction displaces the aortic annulus and produces a force that stretches the ascending aorta. We hypothesized that aortic stiffening increases this previously ignored component of LV load and may contribute to hypertrophy. Conversely, aortic stretch-related work represents stored energy that may facilitate early diastolic filling.

METHODS AND RESULTS

We performed MRI of the aorta and LV in 347 participants (72-91 years old, 189 women) in the Age, Gene/Environment Susceptibility-Reykjavik Study to examine relations of aortic stretch with LV structure and function. Aortic stiffness was evaluated as the product of Young's modulus and aortic wall thickness. Force was computed from Young's modulus and longitudinal aortic strain; work was the integrated product of force and annulus displacement during systole. LV mass and dynamic volume were measured using the area-length method. Filling was assessed from time-resolved LV volume curves. In multivariable models that adjusted for age, sex, height, weight, end-diastolic LV volume, augmentation index, end-systolic pressure, and cardiovascular disease risk factors, higher aortic stiffness was associated with increased LV mass (β=3.0±0.8% per SD, P<0.001; sex interaction, P=0.8). Greater stretch-related aortic work was associated with enhanced early filling in men (β=4.0±0.8 mL/SD; P<0.001), but not in women (β=-0.4±0.7 mL/SD; P=0.6).

CONCLUSIONS

Higher aortic stiffness was associated with higher LV mass, independently of pressure. Higher stretch-related work was associated with greater early diastolic filling in men only. Impaired diastolic recovery of energy stored by systolic proximal aortic stretch may contribute to increased susceptibility to diastolic dysfunction in women.

Echocardiographic evaluation of myocardial strain in patients after transcatheter aortic valve implantation

Introduction

Echocardiographic evaluation of regional myocardial function helps to assess the efficacy of therapeutic interventions and to predict the prognosis and clinical outcomes.

Aim

To assess whether myocardial strain can be useful in estimation of left ventricle (LV) function in patients who have undergone transcatheter aortic valve implantation (TAVI).

Material and methods

Twenty-six patients with severe aortic stenosis, who successfully underwent TAVI, were enrolled in the study. Left ventricular peak systolic longitudinal strain (LV PSLS) was obtained before and 1 year after the procedure. Analysis included the potent influence of factors such as sex, LV ejection fraction (LVEF), type of prosthesis implanted or the type of the approach on LV PSLS values.

Results

We observed a significant improvement in LV PSLS values after TAVI (–10.9 ±5.7 vs. –13.4 ±4.7, p < 0.05). Men had better improvement in LV PSLS after TAVI, but their starting values were considerably lower (M: –10.7 ±4.5 before vs. –13.3 ±4.9 after, p < 0.05; W: –11.8 ±6.8 before vs. –11.9 ±5.6 after, p = NS). Patients with starting LVEF ≤ 40% benefited from the procedure (LV PSLS: –10.3 ±6.4 before vs. –13.7 ±2.9 after, p < 0.05), but in the group of patients with the higher starting LVEF no significant changes in LV PSLS were observed. We also did not note any differences in LV PSLS depending on type of the prosthesis implemented (Edwards Sapiens/CoreValve). Patients in whom the prostheses were implemented via the femoral approach only presented significant increase in LV PSLS values (before: –10.4 ±6.7 vs. after: –13.6 ±3.7, p < 0.05).

Conclusions

The TAVI results in improvement of LV systolic function according to LV PSLS values. Some factors, especially lower baseline LVEF, are related to increased benefit in LV PSLS after TAVI.

The value of assessing myocardial deformation at recovery after dobutamine stress echocardiography

Background

The purpose of this study was to evaluate whether performing an assessment of myocardial deformation using speckle tracking imaging during the recovery period after dobutamine stress echocardiography (DSE) allows detection of significant coronary artery disease (CAD) in patients with chest discomfort.

Methods

DSE and coronary angiography were performed in 44 patients with chest discomfort. The mean global longitudinal peak systolic strain (GLS) was measured at rest, at low stress (dobutamine infusion rate of 10 µg/kg/min) and at recovery (5 min after cessation of dobutamine infusion) of DSE using automated function imaging with apical views. Fractional flow reserve (FFR) was also performed in patients with intermediate coronary stenosis. CAD was defined as having a ≥ 70% diameter stenosis on coronary angiography or as having a FFR < 0.8. Patients were divided two groups based on the absence or presence of CAD [CAD (-) group vs. CAD (+) group].

Results

There were no significant differences in the clinical characteristics and results of conventional echocardiography between the two groups. GLS at recovery was lower in the CAD (+) group than in the CAD (-) group (-18.0 ± 3.4% vs. -21.0 ± 1.9%, p = 0.003). The optimal cutoff of GLS at recovery for detection of CAD was -19% (sensitivity of 70.6%, specificity of 83.3%).

Conclusion

Assessment of GLS at recovery of DSE is a reliable and objective method for detection of CAD. This finding may suggest that systolic myocardial stunning remains even after recovery of wall motion abnormalities in patients with CAD.