There has been a rising interest in the use of strain imaging in echocardiography to better qualify left and right ventricular function and help diagnose various types of cardiomyopathy. But there are still barriers to wider use, namely reimbursement.
Cardiovascular Business spoke about these trends with strain imaging expert Marielle Scherrer-Crosbie, MD, PhD, director of the cardiac ultrasound laboratory and a professor of medicine at the Hospital of the University of Pennsylvania, at the American Society of Echocardiography (ASE) 2023 meeting.
"Myocardial strain or myocardial deformation, it's certainly a very powerful tool in the echo toolbox, and there's been a wealth of literature that really shows its prognostic value. It's an index that's more sensitive than left ventricular ejection fraction (LVEF), and that in a variety of pathology precedes the decrease in LVEF and is able to predict it. Since we know that a decrease of LVEF is linked to an increase in heart failure and cardiovascular events, it seems like it's a good tool to use in terms of its practical application," Scherrer-Crosbie explained.
However, she pointed out several challenges associated with strain echocardiography. Interpretability of data is crucial, requiring careful assessment of tracking quality and proper acquisition of strain images. Issues such as poor image quality and improper points where measurements are taken can significantly impact the reliability of strain. Furthermore, for strain to be reliable and consistent, especially across a a series of exams, it must either be measured on the same machine or through a vendor-independent software.
"You can't just press on a button and expect that the result will be correct every time and you can rely on it," she said.
Scherrer-Crosbie added that a certain level of expertise is required to ensure the measurements are taken correctly and that the same software is used each time for that patient to enable reproducibility. This can be difficult due to the variability between vendor systems and sonographers. But, that is now changing thanks to automation with artificial intelligence (AI).
AI is helping automate strain imaging
Some cardiac ultrasound vendors are now offering FDA-cleared auto strain imaging features using AI. This helps level the playing field to reduce variability and the need for high levels of experience between operators.
The automation aims to save sonographers time and improve patient access. Scherrer-Crosbie acknowledged there is potential for wider adoption of strain imaging if it becomes easier to use and automation is built into echo systems. However, she stressed the importance of verifying the AI got things right.
"As the reader, you still need to go over it and make sure that you're not reporting something that doesn't make sense," she explained.
A few echo vendors now offer some level of automation for strain automation. A good example of where things are going with AI and echo is recently launched Acuson Origin cardiovascular ultrasound system. It offers robust AI capabilities that allow it to identify the anatomy being imaged and anticipate the next steps needed to advance patient care. This includes completely automated strain assessments in a couple seconds and algorithms to automate about 500 different measurements.
Echo AI vendor Dia also released an OEM vendor-neutral automated strain algorithm that is used on several vendors' hand-held point-of-care ultrasound (POCUS) systems for faster assessments bedside, urgent care and office settings. Philips purchased Dia in 2022.
How is cardiac strain imaging being used?
The use of strain is particularly beneficial in patients with LVEF at the lower limits of normal. A significant decrease in strain, especially in patients with borderline LVEF, can serve as an alert for subtle cardiac dysfunction, Scherrer-Crosbie explained.
The ability of strain to detect those subtle differences in cardiac function is leading to earlier detection or confirmation of numerous disease states, including heart failure, hypertrophic cardiomyopathy (HCM), cardiac amyloidosis, myocardial infarction, left bundle branch block (LBBB), post infarction aneurism, and other conditions.
Lack of reimbursement has limited adoption of strain echo
Despite its clinical utility, reimbursement issues remain a significant hurdle for widespread adoption of strain echocardiography.
Scherrer-Crosbie highlighted the challenges in obtaining reimbursement for strain imaging, especially in cases of left ventricular hypertrophy where abnormal strain may indicate subtle myocardial function impairment. While strain is recognized as an established method for assessing left ventricular function in cardio-oncology, recent studies have questioned its efficacy compared to EF-guided therapy.
Some insurance companies are reluctant to reimburse for strain, and that is something ASE is working on in through advocacy efforts, she said.
"There are still some issues on the reimbursement of strain. Certainly it's an established way of looking at LV function in cardio-oncology. Often we have difficulties in getting a reimbursement for the strain, which is something we're working on because it can be also very helpful in patients," Scherrer-Crosbie said.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: dfornell@innovatehealthcare.com