Left ventricular longitudinal strain is associated with mitral annular fractional area change in healthy subjects-Results from the three-dimensional speckle tracking echocardiographic MAGYAR-Healthy Study

Normative healthy reference values for global and segmental 3D principal and geometry dependent strain from cine cardiac magnetic resonance imaging

3-Dimensional (3D) myocardial deformation analysis (3D-MDA) enables novel descriptions of geometry-independent principal strain (PS). Applied to routine 2D cine cardiovascular magnetic resonance (CMR), this provides unique measures of myocardial biomechanics for disease diagnosis and prognostication. However, healthy reference values remain undefined. This study describes age- and sex-stratified reference values from CMR-based 3D-MDA, including 3D PS. One hundred healthy volunteers were prospectively recruited following institutional ethics approval and underwent CMR imaging. 3D-MDA was performed using validated software. Age- and sex-stratified global and segmental strain measures were derived for conventional geometry-dependent [circumferential (CS), longitudinal (LS), and radial (RS)] and geometry-independent [minimum (minPS) and maximum principal (maxPS)] directions of deformation. Layer-specific contraction angle interactions were determined using local minPS vectors. The average age was 43 ± 15 years and 55% were women. Strain measures were higher in women versus men. 3D PS-based assessment of maximum tissue shortening (minPS) and maximum tissue thickening (maxPS) were greater than corresponding geometry-dependent markers of LS and RS, consistent with improved representation of local tissue deformations. Global maxPS amplitude best discriminated both age and sex. Segmental analyses showed greater strain amplitudes in apical segments. Transmural PS contraction angles were higher in females and showed a heterogeneous distribution across segments. In this study we provided age and sex-based reference values for 3D strain from CMR imaging, demonstrating improved capacity for 3D PS to document maximal local tissue deformations and to discriminate age and sex phenotypes. Novel markers of layer-specific strain angles from 3D PS were also described.

Protective effect of a chronic hypobaric hypoxic environment at high altitude on cardiotoxicity induced by doxorubicin in rats: a 7 T magnetic resonance study

Background

Doxorubicin (DOX)-induced cardiotoxicity (DIC), a major clinical problem, has no effective preventive therapies. We hypothesized that left ventricular (LV) systolic function would be improved in a chronic hypobaric hypoxia environment at high altitude. The purpose of this study was to investigate whether cardiovascular magnetic resonance could reveal the cardioprotective effect of chronic hypobaric hypoxia on DIC.

Methods

In total, 60 rats were randomly assigned to 1 of 6 groups (n=10 per group): the P group (plain), PD group (plain + DOX), HH group (high altitude), HHD4 group (high altitude + DOX for 4 weeks), HHD8 group (high altitude + DOX for 8 weeks), and HHD12 group (high altitude + DOX for 12 weeks). The rats were transported to either Yushu (altitude: 4,250 m) or Chengdu (altitude: 500 m) where they underwent intraperitoneal injection of DOX (5 mg/kg/week for 3 weeks) or saline. Preclinical 7 T cardiovascular magnetic resonance was performed at weeks 4, 8, and 12. Tissue tracking was used to measure LV cardiac function and to analyze global and segmental strains. Subsequently, histological and oxidative stress tests were performed to evaluate the protective effect of a high-altitude environment on DIC.

Results

The left ventricular ejection fraction (LVEF) and global and regional strains in the middle, apical, anterior, septal, inferior, and lateral segments (all P<0.05) were improved in the HHD4 group compared with the PD group. The global strain was significantly greater in absolute value in the HHD8 and HHD12 groups than in the HHD4 group (all P<0.05). Additionally, histological and enzyme-linked immunosorbent assay evaluations supported the in vivo results.

Conclusions

A chronic hypobaric and hypoxic environment at high altitude partially prevented cardiac dysfunction and increased global and regional strain in DIC rat models, thereby minimizing myocardial injury and fibrosis. In addition, by increasing the total duration of chronic hypobaric hypoxia, the global strain was further increased, which was likely due to reduced oxidative stress.

The value of non-invasive myocardial work indices derived from left ventricular pressure-strain loops in predicting the response to cardiac resynchronization therapy

Background

Non-invasive left ventricular (LV) pressure-strain loops (PSLs), which are generated by combining LV longitudinal strain with brachial artery blood pressure, provide a novel method of quantifying global and segmental myocardial work (MW) indices with potential advantages over conventional echocardiographic strain data, which suffers from being load-dependent. This method has been recently introduced in echocardiographic software, enhancing the efficiency of MW calculations. This study aimed to evaluate the role of non-invasive MW indices derived from LV PSLs in predicting cardiac resynchronization therapy (CRT) response.

Methods

A total of 106 heart failure (HF) patients scheduled for CRT were included in the MW analysis. Global and segmental (septal and lateral at the mid-ventricular level) MW indices were assessed before CRT and at a 6-month follow-up. Response to CRT was defined as ≥15% reduction in LV end-systolic volume and ≥1 NYHA functional class improvement at 6-month follow-up compared to baseline.

Results

CRT response was observed in 78 (74%) patients. At baseline, the global work index (GWI) and global constructive work (GCW) were significantly higher in CRT responders than in non-responders (both P<0.05). Furthermore, responders exhibited significantly higher mid lateral MW and mid lateral constructive work (CW) (both P<0.001), but significantly lower mid septal MWI and mid septal myocardial work efficiency (MWE) than non-responders (all P<0.01). Baseline mid septal MWE (OR 0.975, 95% CI: 0.959-0.990, P=0.002) and mid lateral MWI (OR 1.003, 95% CI: 1.002-1.004, P<0.001) were identified as independent predictors of CRT response in multivariate regression analysis. Mid septal MWE ≤42% combined with mid lateral MWI ≥740 mmHg% predicted CRT response, with an optimal sensitivity of 79% and specificity of 82% [area under the receiver operating characteristic curve (AUC) =0.830, P<0.001].

Conclusions

Assessment of MW indices before CRT could identify the marked imbalance in LV MW distribution and can be widely used as a reliable complementary tool for guiding patient selection for CRT in clinical practice.

Normal reference values of three-dimensional speckle-tracking echocardiography-derived mitral annular dimensions and functional properties in healthy adults: Insights from the MAGYAR-Healthy Study

INTRODUCTION

There is a limited number of echocardiographic studies determining mitral annular (MA) dimensions in healthy subjects. The present study aimed to establish normal reference values of three-dimensional speckle-tracking echocardiography-derived MA dimensions and functional properties in healthy adults in relation with age and gender.

METHODS

The present study comprised 298 healthy adult subjects. From this population, 94 subjects were excluded due to inadequate image quality. Therefore the remaining group consisted of 204 subjects with the mean age of 33.88 ± 12.97 years (107 males). The population sample was further divided into age categories: 18-29 years (n = 105; mean age: 24.11 ± 2.98 years, 51 males), 30-39 years (n = 44; mean age: 33.80 ± 2.39 years, 31 males), 40-49 years (n = 19; mean age: 43.47 ± 3.18 years, 11 males) and ≥50 years of age (n = 36, mean age: 57.42 ± 6.11 years, 14 males).

RESULTS

End-diastolic MA dimensions did not change significantly during the decades. End-systolic MA diameter, area, and perimeter were larger over the age of 50 years than in the 18-29 year-old group. MA fractional area change was found smaller over the age of 50 years than in 18-29-year-old group. While end-diastolic MA variables did not show gender-differences, end-systolic MA area and perimeter were lower in females in the 18-29-year-old group.

CONCLUSIONS

End-systolic MA dimensions change over decades, resulting in a special pattern of MA functional properties with significant reduction over the age of 50 years.

Prognostic implications of left ventricular geometry in coronary artery bypass grafting patients

Background

The prognostic implications of left ventricular (LV) mass and geometry have been confirmed in populations with different cardiac diseases. However, the prognostic value of LV geometry in coronary artery bypass grafting (CABG) patients is unclear.

Methods

A total of 2,517 patients undergoing CABG between January 2012 and September 2016 in our cardiac surgery unit were included. Patients were divided into the following 4 groups according to left ventricular mass index (LVMi) and relative wall thickness (RWT): normal geometry, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy.

Results

The median follow-up period was 47.0 months (interquartile range was 32.5-61.3 months). Compared to the normal geometry group, the concentric remodeling group [hazard ratio (HR): 3.023; 95% confidence interval (CI): 1.134-8.060], the eccentric hypertrophy group (HR: 3.422; 95% CI: 1.395-8.398), and the concentric hypertrophy group (HR: 5.399; 95% CI: 2.289-12.735) have higher main adverse cardiovascular and cerebrovascular event (MACCE) risk. Moreover, increased MACCE risk was associated with higher LVMi (HR: 1.015 per 1 g/m² increase in LVMi; 95% CI: 1.005-1.026) and RWT (HR: 1.991 per 0.1-U increase in RWT; 95% CI: 1.343-2.952). We observed similar results concerning mortality. Adding LV geometry to the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II significantly improved the area under the curve (AUC) for MACCE (from 0.621 to 0.703; P=0.042). The addition of LV geometry showed significant integrated discrimination improvement (IDI) and net reclassification improvement (NRI) for MACCE (IDI: 0.043, P<0.001; NRI: 0.200, P<0.001) and death (IDI: 0.018, P=0.020; NRI: 0.308, P=0.002), as was the addition of LVMi and RWT.

Conclusions

LV geometry is an independent and incremental prognostic factor for MACCE and death in CABG patients.

Non-invasive assessment of early and acute myocarditis in a rat model using cardiac magnetic resonance tissue tracking analysis of myocardial strain

Background

Myocardial strain analysis can provide diagnostic and prognostic information for myocarditis. The aim of the present study was to assess early and acute myocarditis in a rat model using cardiac magnetic resonance tissue tracking (CMR-TT) for myocardial strain analysis. We compared the strain's findings with the histological and immunohistochemical results.

Methods

Experimental autoimmune myocarditis (EAM) was induced by footpad injections of porcine cardiac myosin. The rats were examined by 7.0T preclinical CMR at day 14 (n=15) and day 21 (n=16) after EAM induction and the two control groups (each n=15) were also examined at day 14 and day 21, respectively. Using CMR-TT, we found a global peak systolic radial strain (Err_SAX) and a circumferential strain (Ecc_SAX) from the short-axis cine views and a radial strain (Err_LAX) and a longitudinal strain (Ell_LAX) from the long-axis cine views, which were calculated by dedicated TT software. Subsequently, histological and immunohistochemical evaluations were performed.

Results

Ell_LAX significantly decreased in early myocarditis compared with the control (-23.40%±1.48% vs. -22.02%±0.81%, P<0.05). Err_SAX, Ecc_SAX, Err_LAX, and Ell_LAX values significantly reduced in acute myocarditis compared with the controls (Err_SAX: 34.27%±9.80% vs. 49.76%±4.97%, Ecc_SAX: -18.98%±3.69% vs. -24.13±1.23, Err_LAX: 33.21%±10.24% vs. 49.59%±5.69%, and Ell_LAX: -17.75%±3.58% vs. -23.39%±1.48%; P<0.001, respectively). The receiver operating characteristic curve showed that myocardial strain analysis had a good diagnostic performance in early and acute myocarditis. The pathological evaluation revealed that inflammatory lesions began to appear in early myocarditis and peaked in acute myocarditis.

Conclusions

The CMR-TT strain analysis allowed accurate and reliable evaluation of early and acute myocarditis in a rat model, and has the potential to serve as a diagnostic indicator for the assessment of myocardial dysfunction in myocarditis.

A review of current trends in three-dimensional analysis of left ventricular myocardial strain

Three-dimensional (3D) left ventricular (LV) myocardial strain measurements using transthoracic 3D echocardiography speckle tracking analysis have several advantages over two-dimensional (2D) LV strain measurements, because 3D strain values are derived from the entire LV myocardium, yielding more accurate estimates of global and regional LV function. In this review article, we summarize the current status of 3D LV myocardial strain. Specifically, we describe how 3D LV strain analysis is performed. Next, we compare characteristics of 2D and 3D strain, and we explain validation of 3D strain measurements, feasibility and measurement differences between 2D and 3D strain, reference values of 3D strain, and its applications in several clinical scenarios. In some parts of this review, we used a meta-analysis to draw reliable conclusions. We also describe the added value of 3D over 2D strain in several specific pathologies and prognoses. Finally, we discuss novel techniques using 3D strain and suggest its future directions.

Association between advanced interatrial block and small vessel diseases in the brain

Background

The latest evidence shows the association of atrial cardiopathy with embolic strokes of undetermined source. Advanced interatrial block (aIAB) is an electrophysiological mark of atrial cardiopathy. This study investigated the relationship between aIAB and the burden of silent cerebral small vessel diseases (SVD) on magnetic resonance imaging in the absence of atrial fibrillation (AF) and atrial flutter.

Methods

This cross-sectional study included 499 patients with normal left ventricular ejection fraction (LVEF), who were free of AF, atrial flutter, stroke, and acute coronary syndrome in our hospital. aIAB was ascertained by digital electrocardiograms. Left atrial diameter, LVEF, and left ventricular posterior wall thickness (LVPWT) were measured on echocardiograms. Based on the presence of 4 manifestations of SVD, including white matter hyperintensity (WMH), lacunes, microbleeds, and enlarged perivascular spaces (EPVS) on magnetic resonance imaging, an ordinal SVD score (range, 0-4) was devised to reflect the total burden of cerebral SVD. The ordinal regression model was used to explore the association of aIAB with SVD burden after adjusting for confounding factors.

Results

The mean age was 67.7 years, and 327 (65.5%) were male. A total of 23 (4.6%) patients had aIAB. The number of patients with cerebral SVD scores of 0, 1, 2, 3, and 4 was 92 (18.4%), 122 (24.4%), 190 (38.1%), 83 (16.6%), and 12 (2.4%), respectively. After adjusting for age, sex, hypertension, diabetes, hyperlipidemia, left atrial diameter, LVEF, and LVPWT, the regression model showed a significant association of aIAB with cerebral SVD score (OR =2.408, 95% CI, 1.082-5.366).

Conclusions

Atrial cardiopathy indexed by aIAB was independently associated with a high burden of SVD in the brain.