Evaluation of Seismocardiography (SCG) as a Tool for Assessing Fitness and Predicting Outcomes in Oesophageal Cancer Surgery

Oesophageal cancer is the 8th most common cause of cancer and the 6th leading cause of cancer-related deaths worldwide(West et al., 2016; Liu et al., 2023). Surgery with curative intent has been associated with significant morbidity and mortality despite recent advancements in anaesthesia and surgical techniques(Wu et al., 2014). Good patient selection with optimisation of cardiorespiratory fitness (CRF) is essential to improve surgical outcomes(West et al., 2014; Ozova et al., 2022). This is particularly important given that most oesophageal cancer patients undergo neo-adjuvant treatment (e.g. chemotherapy), which is known to have a significant adverse effect on patient fitness before surgery (mean reduction of 12.1% in VO2Peak) (Jack et al., 2014). A lower baseline level of fitness has also been shown to be associated with morbidity and mortality in patients undergoing treatment with curative intent (Hennis et al., 2011; West et al., 2024). Prehabilitation is now considered the standard of care in oesophageal cancer surgery, with societal guidance recently recommending a baseline fitness assessment to tailor the intervention as well as a means of monitoring response (Walker et al., 2024).

Cardiopulmonary Exercise Testing (CPET) is considered the gold standard in measuring the CRF of an individual by obtaining the maximal volume of oxygen consumed (VO2Peak) in samples of expired gas during a graded effort cycle ergometer test (Krogh et al., 2020; Levett et al., 2018a). However, CPET is a resource-intensive, costly, time-consuming test (requiring up to 60 minutes) and creates a significant time burden on patients with already busy treatment schedules. In a UK survey of prehabilitation practice, 50% of Upper Gastrointestinal (UGI) units used CPET at baseline, with only 80% of these (40% total) using CPET for response assessment (Barman et al. 2024 in revision for publication Annals RCS Eng).

Seismofit® is a device that accurately estimates the VO2Peak using machine learning algorithms incorporating seismocardiography (SCG) and patient parameters such as height, weight, age, and gender. SCG is a process by which vibrations generated by the heart during its regular physiological cycles are characterised and mapped for changes in morphology, frequency, intensity and character(Sørensen et al., 2018). Key advantages of Seismofit® include its inter-test reliability, rapid availability of results (i.e., estimation of fitness in under 3 minutes in an outpatient setting), and accurate estimation of fitness in a resting patient (Hansen et al., 2023a). The accuracy of Seismofit® in comparison to CPET-measured CRF has previously been demonstrated with a Mean Absolute Percentage Error (MAPE) of 12.3% in healthy adult populations(Hansen et al., 2023b). However, there is minimal data on cancer patients, and no studies have correlated VO2Peak generated by Seismofit® to clinical outcomes.

Given the potential benefits of Seismofit® over CPET, this study will investigate its validity in a clinical setting across four major Oesophageal cancer resection centres (Guy's and St Thomas NHS Foundation Trust (GSTT), University Hospitals Southampton (UHS), Royal Marsden NHS Foundation Trust (RM) and Royal Surrey NHS Foundation Trust (RS).

This will be the first study to evaluate the use of Seismofit® in a large volume of oesophageal cancer patients. With correlation to clinical outcomes, this study will serve as the basis for future research into the use of Seismofit® in a clinical setting.