Should we be evaluating the ventricle or the myocardium? Advances in tissue characterization

Influence of Myocardial Ischemia Extent on Left Ventricular Global Longitudinal Strain in Patients After ST-Segment Elevation Myocardial Infarction

Two-dimensional echocardiographic left ventricular (LV) global longitudinal strain (GLS) after ST-segment elevation myocardial infarction (STEMI) is moderately correlated with infarct size and reflects the residual LV systolic function. This correlation may be influenced by the presence of myocardial ischemia. The present study investigated how myocardial ischemia modulates the correlation between LV GLS and infarct size determined with single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in patients with first STEMI treated with primary coronary intervention. A total of 1,128 patients (age 60 ± 11 years) who underwent SPECT MPI for the evaluation of infarct size and residual ischemia were evaluated. LV GLS was measured on transthoracic echocardiography. The time interval between echocardiography and SPECT MPI was 1 ± 1 month. A moderate correlation between echocardiographic LV GLS and infarct size on SPECT MPI was observed (r = 0.58, p <0.001). This correlation was weakened by the presence or extent of ischemia; in the group of patients without ischemia, the correlation between LV GLS and infarct size on SPECT MPI was r = 0.66 (p <0.001), whereas in patients with mild or moderate-to-severe ischemia, the correlations were r = 0.56 and 0.38, respectively (both p <0.001). Moderate-to-severe myocardial ischemia was independently associated with more impaired LV GLS after adjusting for infarct size, age, diabetes mellitus, and hypertension (β 0.60, 95% confidence interval 013 to 1.06). In conclusion, the presence of myocardial ischemia after STEMI impacts on the correlation between echocardiographic LV GLS and infarct size measured on SPECT MPI. Residual ischemia is independently associated with more impaired LV GLS.

Atrial fibrillation per se was a major determinant of global left ventricular longitudinal systolic strain

Atrial fibrillation (AF) may cause systolic abnormality via inadequate diastolic filling and tachycardia-induced cardiomyopathy. Global longitudinal strain (GLS) is a very sensitive method for detecting subtle left ventricular systolic dysfunction. Hence, this study aimed to evaluate whether AF patients had a more impaired GLS, AF was a major determinant of GLS, and determine the major correlates of GLS in AF patients.The study included 137 patients with persistent AF and left ventricular ejection fraction (LVEF) above 50% and 137 non-AF patients matched according to age, gender, and LVEF. Comprehensive echocardiography with GLS assessment was performed for all cases.Compared with non-AF patients, AF patients had a more impaired GLS, a larger left atrial volume index, higher transmitral E wave velocity (E), and early diastolic mitral velocity (Ea) (all P < 0.001) but comparable E/Ea. After adjustment for baseline and echocardiographic characteristics, the presence of AF remained significantly associated with impaired GLS (β = 0.533, P < 0.001). In addition, multivariate analysis of AF patients indicated that faster heart rates and decreased E, Ea, and LVEF were associated with more impaired GLS.This study demonstrated that AF patients had a more impaired GLS than non-AF patients, although LVEF was comparable between the 2 groups. AF was a major determinant of GLS even after adjustment for relevant clinical and echocardiographic parameters.

The importance of speckle tracking echocardiography in the early detection of left ventricular dysfunction in patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by hormonal and metabolic abnormalities and is thought to increase a risk for cardiovascular diseases. In this study we use speckle tracking echocardiography (STE) to evaluate left ventricular (LV) dysfunction in the early period of the disease. We enrolled 31 patients with PCOS and 32 healthy volunteers as a control group. The participants' ages ranged between 18 and 40 years. PCOS was diagnosed according to the Rotterdam criteria. LV strain (LS) and strain rate (SR) were evaluated using apical two-chamber (2C), three-chamber (3C), and four-chamber (4C) imaging. Global LS and SR were calculated as average of three apical views. The waist-to-hip ratio, homeostasis model assessment-insulin resistance (HOMA-IR), and fasting insulin and triglyceride levels were higher in the PCOS group than in the controls (p=0.001, p=0.001, p=0.001, and p=0.005, respectively). In the PCOS group, the mitral A wave, deceleration time (DT), and isovolumetric relaxation time (IVRT) were significantly higher than in the controls (all p<0.05). The LV global longitudinal strain (GLS) and global longitudinal SR systolic (GLSRS) were significantly lower in the PCOS patient group (both p= 0.001). There were strong negative correlations between GLS and both fasting insulin (r=-0.64) and DT (r=-0.62) (both p<0.05). The study demonstrated that PCOS patients had decreased LV function using STE. Therefore, STE imaging appears to be useful for the early detection of subclinical LV dysfunction in patients with PCOS.

Metabolomic approach to profile functional and metabolic changes in heart failure

Background

Heart failure (HF) is characterized by a series of adaptive changes in energy metabolism. The use of metabolomics enables the parallel assessment of a wide range of metabolites. In this study, we appraised whether metabolic changes correlate with HF severity, assessed as an impairment of functional contractility, and attempted to interpret the role of metabolic changes in determining systolic dysfunction.

Methods

A 500 MHz proton nuclear magnetic resonance (¹H-NMR)-based analysis was performed on blood samples from three groups of individuals: 9 control subjects (Group A), 9 HF patients with mild to moderate impairment of left ventricle ejection fraction (LVEF: 41.9 ± 4.0 %; Group B), and 15 HF patients with severe LVEF impairment (25.3 ± 10.3 %; Group C). In order to create a descriptive model of HF, a supervised orthogonal projection on latent structures discriminant analysis (OPLS-DA) was applied using speckle tracking-derived longitudinal strain rate as the Y-variable in the multivariate analysis.

Results

OPLS-DA identified three metabolic clusters related to the studied groups achieving good values for R² [R²(X) = 0.64; R²(Y) = 0.59] and Q² (0.39). The most important metabolites implicated in the clustering were 2-hydroxybutyrate, glycine, methylmalonate, and myo-inositol.

Conclusions

The results demonstrate the suitability of metabolomics in combination with functional evaluation techniques in HF staging. This innovative tool should facilitate investigation of perturbed metabolic pathways in HF and their correlation with the impairment of myocardial function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0661-3) contains supplementary material, which is available to authorized users.

Evaluation of cardiac function by two-dimensional speckle tracking echocardiography in ulcerative colitis patients

PURPOSE

Although ulcerative colitis (UC) shows obvious similarities with other autoimmune diseases, cardiac consequences have not adequately introduced. The aim of our study was to evaluate left ventricular (LV) function in UC patients by using novel echocardiographic parameters.

RESULTS

Forty-five UC patients (mean age 37, 18 female) and 90 age- and sex-matched healthy volunteers (mean age 40, 38 female) included in the study. The mean disease activity score according to partial Mayo score was 2.16 ± 2.13. Mean global longitudinal strain (GLS) and global longitudinal strain rate (GLSR) measurements were significantly lower (-21.16 ± 2.71 vs. -23.36 ± 3.34; p < 0.001 and -1.33 ± 0.24 vs. -1.43 ± 0.24; p = 0.037, respectively), whereas global circumferential (-22.67 ± 3.66 vs. -23.37 ± 3.99; p = 0.140) and global radial strain (43.07 ± 8.58 vs. 44.12 ± 9.32; p = 0.545) measurements of the LV were similar in patients with UC compared with controls. The correlation coefficient (r) between GLS and partial Mayo score was -0.578 (p < 0.001).

CONCLUSION

Our study suggests that systolic cardiac deformation values are impaired in UC patients. Reduced GLS and GLSR might be an early indicator of cardiac involvement in this population.

Early assessment of percutaneous coronary interventions for chronic total occlusions analyzed by novel echocardiographic techniques

OBJECTIVE

Successful revascularization of chronic total occlusions has been associated with improved left ventricular systolic function, reduced anginal symptoms, increased exercise capacity, and increased survival. This study was conducted to determine the impact of revascularization in chronic total occlusion on left ventricular function using novel echocardiographic techniques.

METHODS

A total of 129 patients with chronic total occlusion who underwent revascularization between April 2011 and November 2012 were included in this study. Echocardiographic assessments with two-dimensional speckle tracking echocardiography and real-time three-dimensional echocardiography were performed before the procedure and one month after the procedure. The left ventricular ejection fraction, left ventricular volumes, and three-dimensional systolic dyssynchrony index were quantified.

RESULTS

An immediate procedural success was obtained in 118 patients (91.5%). There were no acute or subacute stent thromboses during follow-up. The mean left ventricular ejection fraction significantly increased (p<0.001), while the left ventricular end-diastolic and end-systolic volumes significantly decreased (p = 0.001 and p<0.001, respectively). The three-dimensional systolic dyssynchrony index also decreased significantly (p<0.001). The global longitudinal strain showed a significant increase after successful revascularization (p<0.001). An increase in the global longitudinal strain was correlated with an increase in the left ventricular ejection fraction (r = 0.27, p = 0.02). The patients with a left ventricular ejection fraction ≥50% displayed a greater improvement in the global longitudinal strain, and the patients with diabetes showed less improvement.

CONCLUSIONS

Using novel echocardiographic techniques, our results showed that restoring the coronary blood flow in chronic total occlusion patients reduces the left ventricular volumes and improves the left ventricular ejection fraction and the global longitudinal strain of hibernating myocardium.

Tissue Doppler imaging of the left ventricle in healthy elderly females does not support the concept of “isolated” diastolic dysfunction

The concept of "isolated" left ventricular diastolic dysfunction has recently been challenged, since left ventricular contraction abnormalities can be demonstrated in subjects with normal left ventricular ejection fraction (EF). In this study of 35 healthy females (aged 65--80 years) with EF>50%, the ratio of peak early transmitral flow velocity to peak early diastolic myocardial velocity (E/Em) correlated significantly with peak systolic myocardial longitudinal velocity (Sm) (r=-0.57, p<0.0001), assessed as an average in six basal left ventricular segments. E/Em correlated also with age (r=0.51, p<0.002), but not significantly with ambulatory daytime systolic blood pressure (r=0.32, p=0.06), nor with left ventricular mass. In conclusion, there is a significant correlation between left ventricular diastolic and systolic function also in an apparently healthy population when adequately sensitive methods are used, in terms of tissue Doppler assessment of the left ventricular longitudinal motion. Although age may influence left ventricular longitudinal motion, an influence of arterial blood pressures is unclear.

Use of myocardial strain to assess global left ventricular function: a comparison with cardiac magnetic resonance and 3-dimensional echocardiography

BACKGROUND

Ejection fraction (EF) plays a prominent role in clinical decision making but remains dependent on image quality and left ventricular geometry. Using magnetic resonance imaging (MRI-EF) as the reference standard, we sought whether global longitudinal strain (GLS) could be an alternative to the measurement of EF.

METHODS

Manual and semi-automated tracing was used to measure Simpson's biplane ejection-fraction (2D-EF) and 3D ejection fraction (3D-EF) and MRI in 62 patients with previous infarction. Global longitudinal strain was measured by 2-dimensional strain (2DS) in the apical views. Automated EF was calculated using speckle tracking to detect the end-diastolic and end-systolic endocardial border.

RESULTS

Strain curves were derived in all segments, with artifactual curves being excluded. The correlation of GLS with MRI-EF (r = -0.69, P < .0001) was comparable to that between 3D-EF and MRI (r = 0.80, P < .0001), and better than that between 2D-EF (r = 0.58, P < .0001) or automated EF and MRI (r = 0.62, P < .0001). To convert GLS into an equivalent MRI-EF, linear regression was used to develop the formula EF = -4.35 (strain + 3.9). Of the 32 patients with a normal MRI-EF (> or =50%), 75% had normal systolic function by GLS, whereas 85% of patients were recognized as having a normal 3D-EF. Fewer patients were recognized as normal by 2D-EF (70%, P = .14) and automated-EF (61%, P = .04). In those with >6 abnormal segments, the correlation of GLS with MRI-EF improved significantly (r = -0.77, P < .0001) and was similar to 3D-EF (r = 0.76, P < .0001).

CONCLUSION

Global longitudinal strain is an effective method for quantifying global left ventricular function, particularly in patients with extensive wall motion abnormalities.

Obesity cardiomyopathy: diagnosis and therapeutic implications

Obesity is associated with an increased risk of heart failure. Apparently healthy obese individuals can, however, exhibit subclinical left ventricular dysfunction. The use of myocardial imaging techniques to detect this subclinical change could have important management implications with respect to initiating prophylactic therapy. In this Review, we evaluate possible pharmacologic and nonpharmacologic strategies for treating obesity cardiomyopathy in the context of currently understood mechanisms, including myocardial remodeling and small vessel disease, and more speculative mechanisms such as insulin resistance, and activation of the renin-angiotensin-aldosterone and sympathetic nervous systems.

Quantitative left ventricular systolic function: From chamber to myocardium

One of the most common indications for obtaining a Doppler echocardiographic study is to ascertain left ventricular (LV) systolic function. There are many ways in which LV function can be determined, but an important assumption that is often overlooked is that every measure that we commonly use is only a surrogate marker of LV function due to the fact that it is impossible to characterize the complex geometric and volumetric function of the ventricle (or myocyte) in a single number. Stated in another way, there is no one perfect measure of LV function. The ejection fraction has emerged as the preeminent method to express LV performance, but although ejection fraction is universally accepted, there are a number of other techniques that can assess LV function and, when taken together, provide a more comprehensive picture both of global and regional LV function. Each of these measures (including ejection fraction) has variable dependence on loading conditions, heart rate, and geometric position that limits its accuracy. Understanding the limitations of each measure will allow the physician to more intelligently understand the true status of the myocardium.

Prognostic role of subclinical left ventricular abnormalities and impact of transplantation in chronic kidney disease

OBJECTIVE

The outcome of patients with chronic kidney disease (CKD) is influenced by overt left ventricular (LV) abnormalities. We sought the predictive value and treatment response of subclinical LV dysfunction in CKD.

METHOD

Resting and dobutamine stress echocardiography were used to identify LV enlargement, dysfunction, or ischemia in 176 patients with CKD. In 129 patients who had normal dobutamine stress echocardiography, myocardial tissue characterization was performed using tissue Doppler imaging and integrated backscatter. Clinical, biochemical, and echocardiographic parameters were recorded at baseline, and patients were followed up for cardiac events and all-cause mortality over 2.4 years. Follow-up echocardiographic and tissue characterization parameters were performed in 80 patients.

RESULTS

Previous cardiac history (HR 5.2, P = .002) and serum phosphate (HR 6.2, P = .001) were independent clinical predictors of events (model chi2 = 20.9). Diastolic tissue velocity (HR 0.8, P = .05) was an independent predictor of outcome, and its addition to clinical assessment added incremental prognostic information (model chi2 = 24.8, P < .001). Patients who underwent transplantation (n = 45) showed reduction of wall thickness (P < .001) and LV volumes (P < .001) and increases in diastolic tissue velocity (P = .007) and strain (P = .001), whereas these measurements worsened in those who remained on dialysis.

CONCLUSION

In patients with CKD, subclinical LV dysfunction is associated with adverse outcome. Subclinical disease can be improved by transplantation but progresses in patients who continue on dialysis.

Alterations in Myocardial Characteristics Associated With Obesity: Detection, Mechanisms, and Implications

Hypertension, obstructive sleep apnea, and coronary artery disease all contribute to the myocardial dysfunction in obesity. However, the development of sensitive cardiac imaging techniques has enabled detection of myocardial structural and functional changes independently attributable to obesity, at the preclinical stage. This review will evaluate the evidence for myocardial disease in this setting, its significance, important mechanisms, preclinical detection, and possible therapeutic implications.

Usefulness of Ventricular Longitudinal Contractility Assessed by Doppler Tissue Imaging in the Prediction of Reverse Remodeling in Patients with Severe Left Ventricular Systolic Dysfunction

OBJECTIVE

We sought to test if assessment of ventricular longitudinal contractility (LC) by Doppler tissue imaging (DTI) can predict reverse remodeling (RR) of left ventricular (LV) dysfunction resulting from medical treatment.

METHODS

DTI was performed in 35 patients with nonischemic LV dysfunction (ejection fraction 26 +/- 7%) and LC was assessed at the 4 different basal segments of the LV walls (septal, lateral, inferior, and anterior) using myocardial velocity curves and strain measurements; the peak systolic or delayed longitudinal contraction velocity of LV walls only with concomitant negative strain were measured and added to represent LC of each patient (LC by DTI). Successful RR was defined as a reduction of LV end-systolic volume of greater than 15%.

RESULTS

RR was observed in 13 patients (37%, group A). Initial LV ejection fraction was similar in patients who did and did not achieve RR (group B). Compared with group B, group A showed shorter QRS interval (110 +/- 36 vs 136 +/- 28 milliseconds, P = .022), shorter symptom duration (2.3 +/- 3.5 vs 4.2 +/- 3.4 years, P = .047), lower prevalence of left bundle branch block (23% vs 59%, P = .039), and higher value of LC by DTI (9.6 +/- 3.5 vs 6.3 +/- 3.6 cm/s, P = .011). Multivariate analysis revealed that symptom duration less than 2 years (odds ratio = 8.0, 95% confidence interval = 1.3-47.2, P = .022) and LC by DTI (odds ratio = 1.3, 95% confidence interval = 1.0-1.7, P = .019) were independent predictors of RR.

CONCLUSIONS

DTI provides a new index of LC, which is useful for predicting RR in patients with severe LV dysfunction.

Tissue Doppler imaging for evaluation of myocardial function in patients with diabetes mellitus

PURPOSE OF REVIEW

Heart failure and diabetes mellitus are frequently associated, and diabetes appears to potentiate the clinical presentation of heart failure related to other causes. The purpose of this review is to examine recent advances in the application of tissue Doppler imaging for the assessment of diabetic heart disease.

RECENT FINDINGS

Recent studies have documented that both myocardial systolic and diastolic abnormalities can be identified in apparently healthy patients with diabetes and no overt cardiac dysfunction. Interestingly, these are disturbances of longitudinal function, with compensatory increases of radial function-suggesting primary involvement of the subendocardium, which is a hallmark of myocardial ischemia. Despite this, there is limited evidence that diabetic microangiopathy is responsible-with reduced myocardial blood volume rather than reduced resting flow, and at least some evidence suggesting a normal increment of tissue velocity with stress. Finally, a few correlative studies have shown association of diabetic myocardial disease with poor glycemic control, while angiotensin converting enzyme inhibition may be protective.

SUMMARY

Tissue Doppler imaging (and the related technique of strain rate imaging) appears to be extremely effective for the identification of subclinical LV dysfunction in diabetic patients. It is hoped that the recognition of this condition will prompt specific therapy to prevent the development of overt LV dysfunction.

Alterations of left ventricular myocardial characteristics associated with obesity

BACKGROUND

Obesity is associated with heart failure, but an effect of weight, independent of comorbidities, on cardiac structure and function is not well established. We sought whether body mass index (BMI) and insulin levels were associated with subclinical myocardial disturbances.

METHODS AND RESULTS

Transthoracic echocardiography, myocardial Doppler-derived systolic (sm) and early diastolic velocity (em), strain and strain rate imaging and tissue characterization with cyclic variation (CVIB), and calibrated integrated backscatter (cIB) were obtained in 109 overweight or obese subjects and 33 referents (BMI <25 kg/m2). BMI correlated with left ventricular (LV) mass and wall thickness (P<0.001). Severely obese subjects (BMI >35) had reduced LV systolic and diastolic function and increased myocardial reflectivity compared with referents, evidenced by lower average long-axis strain, sm, cIB, lower CVIB, and reduced em, whereas LV ejection fraction remained normal. Differences in regional or global strain, sm, and em were identified between the severely obese (BMI >35) and the referent patients (P<0.001). Similar but lesser degrees of reduced function by sm, em, and basal septal strain and increased reflectivity by cIB were present in overweight (BMI, 25 to 29.9) and mildly obese (BMI, 30 to 35) groups (P<0.05). Although tissue Doppler measures were not associated with duration of obesity, they did correlate with fasting insulin levels and reduced exercise capacity. BMI was independently related to average LV strain (beta=0.40, P=0.02), sm (beta=-0.36, P=0.002), and em (beta=-0.41, P<0.001).

CONCLUSIONS

Overweight subjects without overt heart disease have subclinical changes of LV structure and function even after adjustment for mean arterial pressure, age, gender, and LV mass.