Can activity trackers shed light on the prognosis of coronary artery disease?

This editorial refers to ‘Impact of activity trackers on secondary prevention in patients with coronary artery disease: a systematic review and meta-analysis’, by T. Kaihara et al. doi:10.1093/eurjpc/zwab146. Appropriate regular exercise is important for secondary prevention in most types of heart disease.1 Increased daily activity is closely associated with decreased all-cause mortality and cardiovascular mortality even in patients with coronary artery disease (CAD) who have experienced acute myocardial infarction or suffer from angina.2,3 It remains beneficial after percutaneous coronary interventions and coronary artery bypass grafting.2,3 Exercise can be measured by frequency, intensity, duration, type, and gradual increase or revision.4 Temporal factors such as the frequency and continuity of exercise, as well as exercise intensity, are important contributors to the physical effects of exercise.5 There may be various negative influences on a patient’s motivation to begin and maintain an exercise regimen. These can include patient characteristics; the severity of the disease and environmental factors, such as the patient’s family, the quality of nursing, and the patient’s economic status. Finding successful methods of motivating patients to engage in exercise is an important, as yet unsolved, problem. Recently, activity trackers have emerged as important auxiliary devices with benefits to treatment in all fields of medicine, including cardiovascular diseases.6,7 Activity trackers have enjoyed increasing popularity over the past few years in conjunction with the rise of smartphones. There are many kinds of activity trackers, serving different purposes and designed for different user groups. Common features include measures of pulse, oxygen saturation, blood pressure, electrocardiogram, step counts, and current pace during exercise. They can also be used to set exercise goals and limits. Some feature alert functions that prevent patients from exceeding safe levels of exercise intensity or act as reminders to exercise. Some activity trackers connect to social networking services that provide appropriate advice and encouragement. In addition to exercise, many trackers also include programmes designed to help improve diet and sleep patterns (Figure 1). There has been considerable research interest in the effect of activity trackers on heart disease prognosis,8,9 especially CAD. However, until recently, there have been no systematic reviews or meta-analyses on this topic. Relationship between the use of activity trackers and the secondary prevention of CAD. CAD, coronary artery disease; LDL-C, low-density lipoprotein cholesterol; MACE, major adverse cardiovascular events; QoL, quality of life; VO2, oxygen consumption. Reproduced from PIXTA Inc. Relationship between the use of activity trackers and the secondary prevention of CAD. CAD, coronary artery disease; LDL-C, low-density lipoprotein cholesterol; MACE, major adverse cardiovascular events; QoL, quality of life; VO2, oxygen consumption. Reproduced from PIXTA Inc. Kaihara et al.10 have conducted the first systematic review and meta-analysis showing the effects of activity trackers on secondary prevention in patients with CAD. They found that the use of activity trackers significantly increases peak oxygen consumption (VO2), decreases the incidence of major adverse cardiovascular events (MACE) and has a positive impact on patient’s quality of life. However, no effect on low-density lipoprotein cholesterol (LDL-C) levels was observed in any of the studies reviewed, which had an average observation period of around 6 months. Given the remarkable development and rise in popularity of activity trackers in recent years, there has been insufficient research into the different types, the duration of daily use and their contribution to secondary prevention in CAD patients, particularly long-term secondary prevention. In addition, the types of CAD, the activity trackers adopted and the definitions of MACE vary between studies. This is likely to have caused some inconsistencies in the results of the Kaihara et al.10 study. Soon, there will undoubtedly be more studies on this subject, and more data will be collected. It is hoped that these will include more consistent definitions of MACE, types of CAD, and types of activity trackers that include daily use durations and longer follow-ups. The study by Kaihara et al.10 also considered the effects of activity trackers on changes in LDL-C in CAD patients. The participants in the study were CAD patients, and while the analysis of LDL-C was of interest, no relationship was found between the use of activity trackers and changes in LDL-C levels.10 This is important as the reduction of LDL-C is recommended for the secondary prevention of CAD.11 However, while exercise and nutrition management using activity trackers did not have a significant effect on LDL-C, they are not necessarily ineffective for this purpose. More research with different trackers should be performed on this in the future. At present, there are two major concerns about activity trackers. First, while there is strong evidence that the use of activity trackers can improve adherence to an exercise regimen, some people, such as elderly patients, find it difficult to maintain their use of activity trackers.8 It would be desirable to develop a product that is easier to use, with either minimal or less complicated functions that are easy for elderly patients to carry with them. Factors other than age, such as the severity of CAD, gender, economic status, and educational backgrounds are all likely to affect individual responses to the use of activity trackers. On the contrary, successful ongoing experience of maintaining a healthy lifestyle through activity tracker use may contribute to their more frequent use (Figure 1). Second, for safety purposes, healthcare professionals need to be able to evaluate and advise individual patients with CAD on the best way to use their activity trackers, based on the health of that patient. In the meta-analysis by Kaihara et al.,10 only those studies, in which evaluations of tracker users were performed by healthcare professionals, were selected for analysis. Such evaluations and advice may improve the adherence of individual patients to activity trackers and lead to better clinical outcomes. It would also be of value if data from activity trackers could be shared with and viewed on electronic medical records, but this is currently difficult due to the need to protect personal information. This is expected to become more acceptable as the usefulness of activity trackers for secondary prevention becomes more widely recognized. In summary, Kaihara et al.’s10 systematic review and meta-analysis on the effect of activity tracers on secondary prevention in CAD patients is a useful guide for the direction of future studies. The use of activity trackers by CAD patients may increase adherence to exercise, leading to improved peak VO2, and a reduced incidence of MACE. Furthermore, in the era of COVID-19, the need to stay at home and avoid interaction with others is likely to have reduced the amount of exercise gained from walking, sports, and other outdoor pursuits and from social activities, including group rehabilitation.12 The use of activity trackers may minimize such decreases in activity or help people to break habits of inactivity formed during COVID-19 lockdown. It is hoped that further research will generate more evidence regarding the benefits of trackers and their optimal use for secondary prevention in CAD patients. Conflict of interest: The authors declare no conflicts of interest concerning this research, authorship and/or publication of this article. Data availability The data underlying this article will be shared on reasonable request to the corresponding author. The opinions expressed in this article are not necessarily those of the Editors of the European Journal of Preventive Cardiology or of the European Society of Cardiology.