Introduction:
A substantial proportion of patients with heart failure (HF) exhibit mitral regurgitation (MR) , leading to impaired functional capacity, quality of life and prognosis. Conventional clinical classifications of HF symptoms, such as the New York Heart Association (NYHA) class, do not involve an objective and quantitative assessment of functional capacity. Meanwhile activity tracking devices experience broad commercial usage among healthy individuals and patients alike and gain rising significance for HF management. Therefore, we evaluated the usability of wearable tracking devices to assess the clinical functional capacity of patients with severe MR.
Methods:
17 patients with symptomatic severe MR were enrolled into this study. The collected dataset included clinical baseline characteristics, echocardiographic and invasive hemodynamic parameters, Minnesota Living with Heart Failure Questionnaire (MLWHFQ) score, 6-minute walk test (6MWT), cardiopulmonary exercise testing (CPET) and data obtained from a commercial wearable tracking devices (WTD) (Garmin vivoactive 3, Garmin, Switzerland).
Results:
A total of 17 patients were included (mean age 75,35 ± 6,8, 41,2 % female, 65% secondary MR). Median left ventricular ejection fraction was 49%. Eleven patients were admitted with MI grade III and 6 with MI-Grade IV. In patients with higher MR grade WTD revealed higher average (69.4 vs. 52.0 bpm, p = 0.034) and maximum heart rate (113.4 vs. 99.0 bpm,
p = 0.03). No further differences regarding baseline characteristics of functional assessment were identified.
Patients were then stratified by median daily step count (≥ vs. < 5,122 steps). While there were also no significant differences in clinical, echocardiographic or hemodynamic characteristics, patients with higher daily step count had significantly higher overall functional capacity: they achieved higher results in 6MWT (445.4 vs. 275.1 m, p = 0.035), higher workload on CPET (%Watt/target 89.5 vs. 62.14 %, p = 0.015), and higher peak oxygen consumption (VO2max 18.04 vs. 12.29 ml/min/kg, p = 0.042).
Strikingly, while the conventional NYHA symptom class showed only modest correlation with objective functional capacity by peak VO2 (Pearson coefficient -0.37, p = 0.15) daily step count by WTD correlated significantly and positively(Pearson coefficient 0.55, p = 0.034). Furthermore, correlation of daily step count with multiparametric severity of HF symptoms according to MLWHFQ was substantial and borderline significant (Pearson coefficient -0.45, p = 0.07).
Conclusion:
In patients with HF and severe MR, daily step count by WTD assessment correlates with objective functional capacity regardless of MR severity or comorbidities. Activity tracking devices could be a valuable tool for diagnostic and therapeutic management.
