Author + information
- Received October 30, 2017
- Revision received July 11, 2018
- Accepted July 11, 2018
- Published online August 6, 2018.
- Hong Yang, MB, PhDa,b,
- Leah Wright, BSa,b,
- Tomoko Negishi, MDa,b,
- Kazuaki Negishi, MD, PhDa,b,
- Jennifer Liu, MDc and
- Thomas H. Marwick, MBBS, PhD, MPHa,b,∗ ()
- aMenzies Institute for Medical Research, Hobart, Tasmania, Australia
- bBaker Heart and Diabetes Institute, Melbourne, Victoria, Australia
- cCardiology Service, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical Center, New York, New York
- ↵∗Address for correspondence:
Dr. Thomas H. Marwick, Baker Heart and Diabetes Institute, Melbourne, P.O. Box 6492, Melbourne, Victoria 3004, Australia.
After a decade of speckle strain, the technique seems set to join a group of transformative innovations that have changed how we use echocardiography. Global longitudinal strain (GLS) has now been recommended as a means of follow-up for patients at risk of cancer therapeutic–related cardiac dysfunction (1). However, although the use of GLS has spread, many clinicians are unfamiliar with the practical process of data acquisition and continue to rely on ejection fraction. The purpose of this iPIX is to facilitate the acquisition and measurement of GLS for following patients in unfamiliar hands by illustrating its application with the most commonly used equipment in the United States.
Strain is analyzed by post-processing of apical views (Table 1).
The derivation of GLS from speckle tracking is slightly different with the software of different manufacturers (Figures 1, 2, 3, and 4⇓⇓⇓⇓), but there are 5 unifying steps: 1) view selection; 2) definition of end systole; 3) tracing; 4) assessing tracking quality; and 5) integration. The analysis steps require minimal time and experience, but need to be followed—strain should not be used as a “black box.”
GLS is a simple parameter that expresses longitudinal shortening as a percentage and is calculated from all modern strain software. There are a number of ways of displaying different aspects of strain, including waveforms (to illustrate contraction delay and temporal dispersion in multiple segments) and parametric displays (which illustrate spatial dispersion throughout the cardiac cycle). These displays are of value for the assessment of regional strain. They are also of use in the quality control of testing subclinical LV dysfunction—where both temporal and spatial dispersion of strain are somewhat unusual and their presence should provide an alert to the presence of possible artifact.
Defining abnormal GLS is less simple than might be desired, because like any ejection-phase parameter, GLS is age-, sex-, and load-dependent. There is some variation between post-processing algorithms of different manufacturers (Table 2), although this is now less than in former years. In adults, GLS <16% is abnormal, GLS >18% is normal, and GLS 16% to 18% is borderline—implying that it is more likely abnormal in a young man with a systolic blood pressure of 110 mm Hg, and likely normal in an 80-year-old woman with a systolic blood pressure of 150 mm Hg. Use of the evolution of GLS from baseline is the preferred metric for the assessment of cardiotoxicity (1).
The automation of this process should not suspend disbelief! Common errors have been previously summarized (3), and include errors of triggering and definition of the region of interest.
Practice is the key to strain analysis. A series of calibration cases are provided in raw data format, readable into EchoPac (General Electric Medical Systems, Milwaukee, Wisconsin). These are provided online (4), and interested persons may access this site, submit their measurements, and receive their results, which can then be compared to those of expert readers.
Dr. Marwick has received research support from General Electric Medical Systems for an ongoing research study on the use of strain for the assessment of cardiotoxicity. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Richard M. Steingart, MD, served as Guest Editor for this paper.
- Received October 30, 2017.
- Revision received July 11, 2018.
- Accepted July 11, 2018.
- 2018 American College of Cardiology Foundation
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- ↵University of Tasmania, Menzies. Strain sUrveillance during Chemotherapy for improving Cardiovascular Outcomes (SUCCOUR Study). Available at: http://menzies.utas.edu.au/research/diseases-and-health-issues/research-projects/strain-surveillance-during-chemotherapy-for-improving-cardiovascular-outcomes-succour-study. Accessed July 11, 2018.