New Myocardial Deformation by 2D Multi-layer Speckle-Tracking Analysis in Healthy Patients: Normal Reference Values and Their Physiologic Determinants

Usefulness of layer-specific strain for evaluating and predicting recovery of left ventricular myocardial function in patients undergoing hybrid coronary revascularization

PURPOSE

This study aimed to determine if layer-specific strain (LSS) can be used to evaluate and predict left ventricular (LV) recovery in patients with multi-vessel coronary artery disease (CAD) undergoing hybrid coronary revascularization (HCR) using speckle tracking echocardiography (STE).

METHODS

A total of 187 consecutive CAD patients who received HCR in our hospital were prospectively enrolled. 30 healthy individuals with matched age and gender were enrolled as a control group. Echocardiography was performed for CAD patients before and 1, 2, and 6 months after HCR. Comprehensive conventional and LSS echocardiography parameters were collected. LV recovery was defined as improvement in LV ejection fraction (LVEF) > 5% at 6-months follow-up compared with baseline. Logistic regression analysis was used to test the correlates of LV recovery. Receiver operating characteristic curve analysis was used to determine the optimal cutoff value of correlates for predicting LV recovery.

RESULTS

LVEF and LV strain in CAD patients were significantly decreased compared with control subjects. Endocardial global longitudinal strain (Endo-GLS) improved significantly at 1-month follow-up (14.2 ± 1.6% vs. 13.8 ± 1.5%, P < 0.05), and LVGLS and global circumferential strain (GCS) improved significantly at 2-months follow-up. Multivariate regression revealed that Endo-GLS, GLS, and SYNTAX score before HCR were independently correlated to LV recovery. Endo-GLS had an optimal cutoff value of 13.2% for predicting LV recovery with sensitivity of 91% and specificity of 78%.

CONCLUSION

LV myocardial systolic function in CAD patients was impaired before HCR and significantly improved after HCR. Endo-GLS was independently correlated to and has optimal predictive value for LV recovery.

Strain Rate Distribution in Layered Myocardium Measured Using Local Velocity Estimator with Multifrequency Phase Differences

Measurement of the myocardial strain rate (SR), with high spatial resolution, is useful in evaluation of the transmurality of myocardial infarction. As the SR distribution is calculated using velocities observed at multiple positions in the heart wall, it is necessary to estimate the local velocity to measure SR distribution. In the present study, our previously proposed local velocity estimator, with multifrequency phase differences, was used to measure SR distribution in the heart wall. The SR distribution measured with the proposed local velocity estimator revealed alternate layers of contraction and relaxation, which were not measured with the conventional velocity estimator with spatial averaging. The reproducibility of the SR distributions was confirmed in three consecutive heartbeats with three subjects. High-spatial-resolution SR measurement with the proposed local velocity estimator will allow myocardial layer-specific analysis in the transmural direction.

Defining the reference range for right ventricular systolic strain by echocardiography in healthy subjects: A meta-analysis

BACKGROUND

Right ventricular (RV) systolic strain has recently demonstrated prognostic value in various cardiovascular diseases. Despite this, the reference range including the lower limit of normal (LLN) and factors associated with RV strain measurements are not well-established. This meta-analysis aimed to determine the mean and LLN of two- (2D) and three-dimensional (3D) right ventricular global (RVGLS), free wall (RVFWLS) and interventricular septal wall (IVSLS) longitudinal strains in healthy individuals and factors that affect strain measurements.

METHODS

In this meta-analysis, Pubmed, Embase and Cochrane databases were searched until 31 July 2020 for eligible studies reporting RVGLS, RVFWLS and/or IVSLS in at least 30 healthy subjects. We pooled the means and LLNs of RV strains by two- (2D) and three- (3D) dimensional echocardiography, and performed meta-regression analyses.

RESULTS

From 788 articles screened, 45 eligible studies totaling 4439 healthy subjects were eligible for analysis. Pooled means and LLNs with 95% confidence intervals for 2D- RV strains were RVGLS -23.4% (-24.2%, -22.6%) and -16.4% (-17.3%, -15.5%) in 27 studies; RVFWLS -26.9% (-28.0%, -25.9%) and -18.0% (-19.2%, -16.9%) in 32 studies; and IVSLS -20.4% (-22.0%, -18.9%) and -11.5% (-13.6%, -9.6%) in 10 studies, and similar results for 3D- RV strains. Right ventricular fractional area change and vendor software were associated with 2D-RVGLS and RVFWLS means and LLNs.

CONCLUSION

We reported the pooled means and LLNs of RV systolic strains in healthy subjects, to define thresholds for abnormal, borderline and normal strains. Important factors associated with RV systolic strains include right ventricular fractional area change and vendor software.