Luisa Graf

Luisa Graf

Master's Thesis

Cardiac Monitoring of Heart Failure Patients using Smartwatches

Katharina Jäger (M.Sc.), Madeleine Flaucher (M.Sc.), Dr.-Ing. Heike Leutheuser, Prof. Dr. Björn Eskofier, Dr. Sebastian Eckl, Patricia Trißler

06 / 2022 – 12 / 2022


Cardiovascular disease was identified as the leading cause of death worldwide in 2019. In the United States, heart failure (HF) accounts for 9.9 % of deaths associated with cardiovascular disease [1]. While the estimated prevalence of HF from 1998 and onwards seemed relatively stable [2], it is projected to rise by 46 % in adults from 2012 to 2030, estimating an increase from 2.4 % to 3.0 % in the total population [1]. With prevalence rising, the estimated overall costs of HF are also projected to grow, suggesting a total increase of 127 % from 30.7 billion to 69.8 billion US dollars in the US in the same period [1].

Based on the 2021 published guidelines by the European Society of Cardiology [3], decompensated HF is the rapid or gradual onset of symptoms severe enough for the patients to require immediate medical intervention. It is associated with high hospitalization, rehospitalization and mortality rates. Early detection of decompensated HF is therefore essential to reduce mortality rates successfully. Typical symptoms and clinical signs are congestion, hypoperfusion, abnormalities in heart sounds (especially third and fourth heart sound) as well as abnormal heart rhythm (tachycardia, arrhythmia) [4].

With the emerging trend of wearables, especially smartwatches, access to biomedical parameters, such as heart rate and oxygen saturation, is becoming more available. Smartwatches can provide meaningful patient-reported parameters, and are therefore useful tools. However, they are not yet standardly integrated into telemonitoring systems for HF patients [5]. Studies suggest that telemonitoring systems show beneficial outcomes when included in the care of HF patients regarding overall mortality and hospitalization rates [6,7]. The reduced hospitalization rate also leads to the reduction of costs for overall HF treatment [8]. Parameters such as heart rate, heart rate variability, oxygen saturation, and ECGs are being investigated in different telemonitoring concepts [9]. Additionally, they can already be captured by modern smartwatches [10]. The potential of self-recorded ECGs has previously been shown with the identification of atrial fibrillation [11]. Besides detecting abnormal heart rhythm, other valuable parameters, e.g., QRS duration, can be extracted from smartwatch-derived data. The importance of a prolonged QRS complex for the prognosis of HF patients has already been discussed extensively [12]. It has been established that 1-lead ECGs accurately measure most baseline intervals, including the QRS complex [13].

Therefore, the goal of this master thesis is to extend the knowledge of how different parameters, extracted and calculated from commercial smartwatch data, can be used to monitor HF and detect decompensation early. For this purpose, relevant parameters that evaluate the health status of HF patients and that can be captured by smartwatch data will be identified based on literature research. A database will be created by conducting a study to validate the previously defined parameters. The study will consist of two groups: a patient group diagnosed with HF and a healthy group. In the final step, differences between the two groups will be investigated.

[1] C. W. Tsao et al., “Heart Disease and Stroke Statistics—2022 Update: A Report From the American Heart Association,” Circulation, vol. 145, no. 8, pp. e153–e639, Feb. 2022, doi: 10.1161/CIR.0000000000001052.
[2] E. E. S. van Riet, A. W. Hoes, K. P. Wagenaar, A. Limburg, M. A. J. Landman, and F. H. Rutten, “Epidemiology of heart failure: the prevalence of heart failure and ventricular dysfunction in older adults over time. A systematic review,” Eur J Heart Fail, vol. 18, no. 3, pp. 242–252, Mar. 2016, doi: 10.1002/ejhf.483.
[3] T. A. McDonagh et al., “2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure: Developed by the Task Force for the diagnosis and treatment of acute and chronic heart failure of the European Society of Cardiology (ESC) With the special contribution of the Heart Failure Association (HFA) of the ESC,” European Heart Journal, vol. 42, no. 36, pp. 3599–3726, Sep. 2021, doi: 10.1093/eurheartj/ehab368.
[4] Arzneimittelkommission Der Deutschen Apotheker (AMK) et al., NVL Chronische Herzinsuffizienz – Langfassung, 3. Auflage. Bundesärztekammer (BÄK); Kassenärztliche Bundesvereinigung (KBV); Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF), 2019. doi: 10.6101/AZQ/000482.
[5] S. M. Werhahn et al., “Designing meaningful outcome parameters using mobile technology: a new mobile application for telemonitoring of patients with heart failure,” ESC Heart Failure, vol. 6, no. 3, pp. 516–525, 2019, doi: 10.1002/ehf2.12425.
[6] J. G. F. Cleland, A. A. Louis, A. S. Rigby, U. Janssens, and A. H. M. M. Balk, “Noninvasive Home Telemonitoring for Patients With Heart Failure at High Risk of Recurrent Admission and Death: The Trans-European Network-Home-Care Management System (TEN-HMS) study,” Journal of the American College of Cardiology, vol. 45, no. 10, pp. 1654–1664, May 2005, doi: 10.1016/j.jacc.2005.01.050.
[7] F. Koehler et al., “Efficacy of telemedical interventional management in patients with heart failure (TIM-HF2): a randomised, controlled, parallel-group, unmasked trial,” Lancet, vol. 392, no. 10152, pp. 1047–1057, Sep. 2018, doi: 10.1016/S0140-6736(18)31880-4.
[8] H. Sydow et al., “Cost-effectiveness of noninvasive telemedical interventional management in patients with heart failure: health economic analysis of the TIM-HF2 trial,” Clin Res Cardiol, Dec. 2021, doi: 10.1007/s00392-021-01980-2.
[9] S. Senarath, G. Fernie, and A. Roshan Fekr, “Influential Factors in Remote Monitoring of Heart Failure Patients: A Review of the Literature and Direction for Future Research,” Sensors, vol. 21, no. 11, Art. no. 11, Jan. 2021, doi: 10.3390/s21113575.
[10] “Apple Watch Series 7,” Apple. (accessed May 05, 2022).
[11] M. V. Perez et al., “Large-Scale Assessment of a Smartwatch to Identify Atrial Fibrillation,” N Engl J Med, vol. 381, no. 20, pp. 1909–1917, Nov. 2019, doi: 10.1056/NEJMoa1901183.
[12] A. Kashani and S. S. Barold, “Significance of QRS complex duration in patients with heart failure,” J Am Coll Cardiol, vol. 46, no. 12, pp. 2183–2192, Dec. 2005, doi: 10.1016/j.jacc.2005.01.071.
[13] H. T. Haverkamp, S. O. Fosse, and P. Schuster, “Accuracy and usability of single-lead ECG from smartphones – A clinical study,” Indian Pacing and Electrophysiology Journal, vol. 19, no. 4, pp. 145–149, Jul. 2019, doi: 10.1016/j.ipej.2019.02.006.


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