gms | German Medical Science

Introduction: Heart failure (HF) is a significant health burden in high-income countries, affecting >10% of the population older than 70 years [1]. Due to its typical trajectory characterized by continuous functional decline, there is a substantial rate of hospital admissions within short intervals, resulting in high costs.

Wearable devices, such as the Apple Watch (Apple Inc., Cupertino, California, U.S.), collect a variety of health parameters in a less obtrusive way compared to conventional medical devices, e.g. Holter recorders [2]. However, in order to ensure data quality, these devices require attention from the users, e.g. regular charging or permanent skin contact. Moreover, some measurements have to be triggered manually, e.g. single-lead electrocardiography (ECG).

Only few studies assessed how to integrate wearable devices into clinical practice [3]. In this project, we aim to explore the adherence of hospitalized HF patients to use the Apple Watch (Series 9) and continuously record health data.

Methods: The study is conducted at the University Medical Center Göttingen within the Department of Cardiology and Pneumology and was approved by the institutional review board (Ethics Approval No. 23/2/24). The study will include 32 HF patients with reduced ejection fraction hospitalized for acute decompensation, i.e. ejection fraction of ≤40%, NTproBNP >1000 pg/ml and at least one sign of either edema, pleural effusion or ascites.

At inclusion, study participants are provided an Apple Watch for the duration of their hospitalization. Study participants will be visited by a study nurse on a regular basis to provide support.

In this work, we analyze to which extent the study participants manage to use the device independently. This includes total wearing time, charging behaviour and triggering ECG acquisition regularly.

Result: To date, recruitment reached 12.5% (4 male, mean age: 77.5 years, mean length of hospital stay: 9.5 days). While contacting potential participants, we did not observe hesitation to join the study.

As there is no direct way to acquire information on wearing time, we analyze the duration when the Apple Watch computed a heart rate. Missing values are interpreted as a device not worn or drained battery. From cumulative wearing time, the charged watch collected data between 67% and 94% of the time, with an average of 86%.

Conclusion: We observed both a high level of adherence in hospitalized HF patients and motivation to actively participate in the study.

However, for many patients it is challenging to trigger ECG acquisition regularly, even with repeated briefings. We assume that in order to collect sufficient ECG data for data-driven research, a study-nurse has to regularly instruct and remind the patients as well as monitor battery levels.

In future work, we aim to analyze the feasibility using automatic signal processing methods, e.g. by computing correct ECG measurement by signal-to-noise ratio analysis [4].

Funding: This work is funded by the DZHK within the “Postdoc Start-up Grant on advancing digital aspects” guideline (81X3300116).

Ethics: The authors declare that a positive ethics committee vote has been obtained. All work involving patient data is carried out under ethics vote (23/2/24).

The authors declare that they have no competing interests.