|Year : 2023 | Volume
| Issue : 2 | Page : 71-73
Myocardial Deformation Imaging Using Echocardiography: A Disruptive Innovation
Editor-in-Chief, Department of Cardiology, Medanta – The Medicity, Gurgaon, Haryana, India
|Date of Submission||13-Aug-2023|
|Date of Acceptance||13-Aug-2023|
|Date of Web Publication||30-Aug-2023|
Senior Director, Clinical and Preventive Cardiology, Medanta Heart Institute, Medanta – The Medicity, Gurgaon, Haryana - 122 001
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bansal M. Myocardial Deformation Imaging Using Echocardiography: A Disruptive Innovation. J Indian Acad Echocardiogr Cardiovasc Imaging 2023;7:71-3
|How to cite this URL:|
Bansal M. Myocardial Deformation Imaging Using Echocardiography: A Disruptive Innovation. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2023 [cited 2023 Oct 3];7:71-3. Available from: https://jiaecho.org/text.asp?2023/7/2/71/384777
The ability to accurately quantify myocardial contractile function has been a long-sought objective of echocardiography. Several different tools have been developed over the years to meet this objective. These include- mitral and tricuspid annular plane systolic excursion with M-mode echocardiography, segmental wall thickening using acoustic quantification or color kinesis, fractional shortening, wall motion score index, left ventricular ejection fraction (LVEF), and lastly, myocardial systolic velocity using tissue velocity imaging. Unfortunately, none of these parameters is a direct measure of myocardial contractility. Only tissue velocity imaging comes close, but it also measures only the myocardial motion relative to the transducer and is influenced by the tethering effect and translation motion of the heart.
The introduction of strain imaging in the late 1990s opened up a new avenue for myocardial function assessment., Initially, the Doppler-based strain was developed, which generated a lot of interest, and many different studies were performed using Doppler strain. However, being a Doppler-based technique, it had inherent limitations and presented many practical challenges. Subsequently, in the early 2000s, speckle-tracking echocardiography (STE) was developed, which completely revolutionized this field., STE is a gray-scale based technique and allows comprehensive assessment of the myocardial deformation. The multidirectional deformation of the left ventricle as well as the right ventricular and left atrial strain can all be assessed using STE. In addition, compared with the Doppler-based strain, STE-based strain assessment is much simpler and faster to perform. The ease of using STE and the growing recognition of the benefits of strain imaging generated tremendous interest in this modality, leading to an explosion in the number of publications in this field [Figure 1].
|Figure 1: The number of publications each year, as shown by a PubMed search with the search phrase “speckle tracking echocardiography”|
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Several different strain measurements and indices can be derived using STE [Table 1]. Of these, the left ventricular (LV) global longitudinal strain (GLS) is the most robust and clinically the most useful. GLS is more sensitive than LVEF to detect subtle changes in the LV myocardial function and can therefore detect subclinical LV systolic dysfunction., It is also more reproducible than LVEF estimation and has much less measurement variability. Even more importantly, GLS has strong prognostic value which is often incremental to clinical, laboratory and conventional echocardiographic parameters. All these attributes make GLS a highly useful parameter, esp. in patients in whom timely recognition of subclinical LV systolic dysfunction may have diagnostic and/or therapeutic implications. Accordingly, GLS is being increasingly used in the evaluation of a wide range of cardiac conditions such as valvular heart diseases, cardiomyopathies, heart failure with preserved ejection fraction, and the patients receiving potentially cardiotoxic cancer therapies., Strain imaging has also been extensively used in research studies involving patients with coronary artery disease (CAD). In this setting, though GLS also has a role, segmental strain is more relevant since CAD affects the LV myocardium in a segmental manner. Many different approaches have been used for incorporating segmental strain in the evaluation of CAD and have generally shown favorable results. Apart from these indications, strain imaging has also been employed in the newer advances such as myocardial work assessment and the machine-learning based automated diagnostic interpretations. Lastly, the strain imaging has also been extended beyond the left ventricle to permit quantification of the right ventricular and left atrial deformation.
|Table 1: Various strain measurements derived using speckle-tracking echocardiography*|
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Although strain imaging has many advantages, it has some important limitations too. Most importantly, even though numerous studies have shown the potential utility of strain imaging, there is unfortunately no data at present to show that strain-guided management can lead to better clinical outcomes. Only one prospective, randomized study (the Strain Surveillance of Chemotherapy for Improving Cardiovascular Outcomes [SUCCOUR]), has been published so far, which compared LVEF-guided versus GLS-guided management in patients receiving potentially cardiotoxic chemotherapy. Strain-guided management was not found to be superior to the EF-guided approach. However, the negative results of this trial are likely to be because of the low incidence of cardiotoxicity in this study, rather than being a reflection of the utility (or futility) of GLS. Nonetheless, more randomized studies are now needed that explore and establish the benefit of strain imaging in different cardiac conditions. Without such a validation, inclusion of GLS in the societal recommendations for clinical management of various cardiac diseases will remain challenging. The second limitation of strain imaging is that apart from GLS, the reproducibility of other strain measurements, especially the segmental strain, is quite suboptimal. This has greatly hindered the use of strain in clinical practice, particularly in patients with CAD in whom segmental strain is required. Apart from these two practical issues, STE has some technical limitations also and careful attention to technical details and expertise are needed to obtain accurate information from STE.
Nevertheless, given the widespread interest in strain imaging, robustness of the fundamental concept underlying strain imaging, and the numerous observational studies showing its benefits, it is imperative for every echocardiographer to be familiar with this modality. Recognizing this need, this issue of the Journal of Indian Academy of Echocardiography and Cardiovascular Imaging provides a compilation of the articles that deal with the different clinical applications of strain imaging. The role of LV strain in common cardiac disorders such as aortic stenosis, aortic regurgitation, mitral regurgitation, CAD, patients undergoing cardiac resynchronization therapy and a range of systemic diseases is discussed. A separate article focusses on the emerging application of strain imaging in the form of myocardial work assessment. In addition, the utility of left atrial and right ventricular strain is also discussed. Put together, these articles provide a comprehensive understanding of all the relevant aspects of myocardial strain imaging at present.
On behalf of the editorial board of the Journal, I invite all our readers to savor this issue. I do sincerely hope that you all will find this issue insightful and a useful resource. I look forward to receiving your valuable feedback about the issue and suggestions to improve it further. You may reach out to us at [email protected].
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