Value of myocardial deformation parameters for detecting significant coronary artery disease

Introduction: The study aimed to evaluate the diagnostic value of global and regional myocardial deformation parameters derived from two-dimensional speckle-tracking echocardiography to detect functionally significant coronary artery stenosis.

Methods: Dobutamine stress echocardiography and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) were performed on 145 patients with a moderate and high probability of coronary artery disease (CAD) and LVEF≥55%. Significant CAD was defined as>50% stenosis of the left main stem,>70% stenosis in a major coronary vessel, or in the presence of intermediate stenosis (50-69%) validated as hemodynamically significant by CMRMPI. Patients were divided in two groups: non-pathological (48.3%) vs pathological (51.7%), according to CAG and CMR-MPI results. Afterwards, off-line speckle-tracking analysis was performed to analyse myocardial deformation parameters.

Results: There were no differences in myocardial deformation parameters at rest between groups, except global longitudinal strain (GLS) and global radial strain (GRS) were significantly lower in the CAD (+) group: -21.3±2.2 vs.-16.3±2.3 (P<0.001) and 39.7±23.2 vs. 24.5±15.8 (P<0.001). GLS and regional longitudinal strain rate (SR) had the highest diagnostic value at high dobutamine dose with AUC of 0.902 and 0.878, respectively. At early recovery, GLS was also found to be the best myocardial deformation parameter with a sensitivity of 78%, specificity 67%, AUC 0.824.

Conclusion: Global and regional myocardial deformation parameters are highly sensitive and specific in detecting functionally significant CAD. The combination of deformation parameters and WMA provides an incremental diagnostic value for patients with a moderate and high probability of CAD, especially the combination with regional longitudinal SR.

Review of ultrasound contrast agents in current clinical practice with special focus on DEFINITY® in cardiac imaging

Echocardiography is the most widely used noninvasive modality to evaluate the structure and function of the cardiac muscle in daily practice. However, up to 15-20% of echocardiograms are considered suboptimal. To enable accurate assessment of cardiac function and wall motion abnormality, the use of ultrasound microbubble contrast has shown substantial benefits in cases of salvaging nondiagnostic studies and enhancing the diagnostic accuracy in daily practice. DEFINITY^® is a perflutren based, lipid shelled microbubble contrast agent, which is US FDA approved for left ventricular opacification. The basis of ultrasound microbubbles, its development, and the clinical role of DEFINITY (characteristics, indications and case examples, side effect profile and existing evidence) is the subject of discussion in this review.

Additional diagnostic accuracy of global longitudinal strain at peak dobutamine stress in patients with moderate pretest probability of coronary artery disease

BACKGROUND

Previous studies confirmed the feasibility of 2D speckle tracking echocardiography (2D STE) during dobutamine stress echocardiography (DSE) in assessing myocardial ischemia in patients with previous myocardial infarction. It is unknown whether it improves the diagnostic accuracy in young patients with intermediate pretest probability for coronary artery disease (CAD) and no prior cardiovascular events.

METHODS

We prospectively studied 101 patients by DSE and STE, followed by coronary angiography within 1 month. Significant CAD was defined as diameter stenosis ≥ 50%. Receiver operating characteristic analysis obtained global longitudinal strain (GLS) cutoff values of significant area under the curve (AUC).

RESULTS

Mean age: 53 ± 8 years, 56% females, 49 had significant CAD (group 1) and 52 had normal/mild CAD (group 2); no significant baseline differences except more males in group 1 (P: .002). DSE sensitivity and specificity for CAD were 79.6% and 92.3%, respectively, positive predictive value (PPV): 90.6%, negative predictive value (NPV): 82.7%, and diagnostic accuracy: 86%. At peak stress, all strain parameters were significantly lower in group 1. However, GLS had the highest AUC: 0.88, P: <.001. GLS cutoff value ≤ -20.5 had 89.8% sensitivity, 84.6% specificity, 84.6% PPV, 89.8% NPV, and 87% diagnostic accuracy. Combining GLS cutoff with DSE had higher AUC than either alone (0.9, P < .001): 95.9% sensitivity, 84.6% specificity, 85.5% PPV, 95.7% NPV, and 90% diagnostic accuracy.

CONCLUSION

2D-STE-derived GLS increases DSE precision to detect CAD in intermediate pretest probability patients: It improves DSE sensitivity, NPV, and accuracy. It is reproducible and has comparable specificity.

Practical tips and tricks in measuring strain, strain rate and twist for the left and right ventricles

Strain imaging provides an accessible, feasible and non-invasive technique to assess cardiac mechanics. Speckle tracking echocardiography (STE) is the primary modality with the utility for detection of subclinical ventricular dysfunction. Investigation and adoption of this technique has increased significantly in both the research and clinical environment. It is therefore important to provide information to guide the sonographer on the production of valid and reproducible data. The focus of this review is to (1) describe cardiac physiology and mechanics relevant to strain imaging, (2) discuss the concepts of strain imaging and STE and (3) provide a practical guide for the investigation and interpretation of cardiac mechanics using STE.

Variability of longitudinal strain measurements: levelling the playing field

Speckle tracking echocardiography offers a unique opportunity to evaluate myocardial function, and global longitudinal strain (GLS) is currently recommended as a measurement of global left ventricular function. To facilitate clinical applicability of the method, collective efforts have been made to standardise strain measurements and to raise awareness of the potential sources of variability. The purpose of this review is to familiarise the reader with the most common sources of variability of longitudinal strain measurements and detail the possible measures to increase the accuracy and reproducibility of strain parameters.

Role of left ventricle deformation analysis in stress echocardiography for significant coronary artery disease detection: A diagnostic study meta-analysis

BACKGROUND

We compared the diagnostic accuracy of longitudinal strain (LS) imaging during stress echocardiography with visual assessment of wall motion (WM) for detecting significant coronary artery disease (CAD).

METHODS

Our systematic search included studies reporting diagnostic measures for LS imaging and visual assessment of WM for detecting significant CAD during stress echocardiography. Summary diagnostic accuracy measures including area under the curve (AUC), sensitivity, specificity, diagnostic odds ratio (DOR), and likelihood ratios (LRs) were estimated.

RESULTS

In thirteen studies with 978 patients, ten studies used invasive coronary angiography as the reference standard. Pooled AUC for diagnosing significant CAD was 0.92 (95% confidence interval [CI] 0.89-0.94) for LS imaging as compared to 0.83 (95% CI 0.80-0.86), P < 0.001 for visual assessment of WM. LS imaging had higher sensitivity (88% [95% CI 84-92] vs 74% [95% CI 68-80], P < 0.001) and comparable specificity to visual assessment of WM (80% [95% CI 72-87] vs 83% [95% CI 74-90], P = 0.592). The DOR for LS imaging and visual assessment of WM was 31 and 15, P = 0.254, respectively. The positive LR was 4.5 for both; negative LR was 0.14 and 0.31, P = 0.002 for LS imaging and visual assessment of WM, respectively.

CONCLUSIONS

Longitudinal strain imaging during stress echocardiography has better diagnostic accuracy for detecting significant CAD as compared to visual assessment of WM. Studies using larger sample size and standardized techniques of strain measurement are required to further ascertain the added advantage of strain measurement over visual assessment alone.

Cardiac Imaging in Heart Failure with Comorbidities

Imaging modalities stand at the frontiers for progress in congestive heart failure (CHF) screening, risk stratification and monitoring. Advancements in echocardiography (ECHO) and Magnetic Resonance Imaging (MRI) have allowed for improved tissue characterizations, cardiac motion analysis, and cardiac performance analysis under stress. Common cardiac comorbidities such as hypertension, metabolic syndromes and chronic renal failure contribute to cardiac remodeling, sharing similar pathophysiological mechanisms starting with interstitial changes, structural changes and finally clinical CHF. These imaging techniques can potentially detect changes earlier. Such information could have clinical benefits for screening, planning preventive therapies and risk stratifying patients. Imaging reports have often focused on traditional measures without factoring these novel parameters. This review is aimed at providing a synopsis on how we can use this information to assess and monitor improvements for CHF with comorbidities.

Characterization of the rdar morphotype, a multicellular behaviour in Enterobacteriaceae

The rdar morphotype, a multicellular behaviour of Salmonella enterica and Escherichia coli is characterized by the expression of the adhesive extracellular matrix components cellulose and curli fimbriae. The response regulator CsgD, which transcriptionally activates the biosynthesis of the exopolysaccharide cellulose and curli, also transforms cell physiology to the multicellular state. However, the only role of CsgD in cellulose biosynthesis is the activation of AdrA, a GGDEF domain protein that mediates production of the allosteric activator cyclic-di-(3'-5')guanylic acid (c-di-GMP). In S. enterica serovar Typhimurium a regulatory network consisting of 19 GGDEF/EAL domain-containing proteins tightly controls the concentration of c-di-GMP. c-di-GMP not only regulates the expression of cellulose, but also stimulates expression of adhesive curli and represses various modes of motility. Functions of characterized GGDEF and EAL domain proteins, as well as database searches, point to a global role for c-di-GMP as a novel secondary messenger that regulates a variety of cellular functions in response to diverse environmental stimuli already in the deepest roots of the prokaryotes.