Multiparameter Monitoring with a Wearable Cardioverter Defibrillator

A wearable cardioverter-defibrillator (WCD) is a temporary treatment option for patients at high risk for sudden cardiac death (SCD) and for patients who are temporarily not candidates for an implantable cardioverter defibrillator (ICD). In addition, the need for telemedical concepts in the detection and treatment of heart failure (HF) and its arrhythmias is growing. The WCD has evolved from a shock device detecting malignant ventricular arrhythmias (VA) and treating them with shocks to a heart-failure-monitoring device that captures physical activity and cardioacoustic biomarkers as surrogate parameters for HF to help the treating physician surveil and guide the HF therapy of each individual patient. In addition to its important role in preventing SCD, the WCD could become an important tool in heart failure treatment by helping prevent HF events by detecting imminent decompensation via remote monitoring and monitoring therapy success.

Feasibility and First Results of Heart Failure Monitoring Using the Wearable Cardioverter–Defibrillator in Newly Diagnosed Heart Failure with Reduced Ejection Fraction

The wearable cardioverter–defibrillator (WCD) is used in patients with newly diagnosed heart failure and reduced ejection fraction (HFrEF). In addition to arrhythmic events, the WCD provides near-continuous telemetric heart failure monitoring. The purpose of this study was to evaluate the clinical relevance of additionally recorded parameters, such as heart rate or step count. We included patients with newly diagnosed HFrEF prescribed with a WCD. Via the WCD, step count and heart rate were acquired, and an approximate for heart rate variability (HRV5) was calculated. Multivariate analysis was performed to analyze predictors for an improvement in left ventricular ejection fraction (LVEF). Two hundred and seventy-six patients (31.9% female) were included. Mean LVEF was 25.3 ± 8.5%. Between the first and last seven days of usage, median heart rate fell significantly (p < 0.001), while median step count and HRV5 significantly increased (p < 0.001). In a multivariate analysis, a delta of HRV5 > 23 ms was an independent predictor for LVEF improvement of ≥10% between prescription and 3-month follow-up. Patients with newly diagnosed HFrEF showed significant changes in heart rate, step count, and HRV5 between the beginning and end of WCD prescription time. HRV5 was an independent predictor for LVEF improvement and could serve as an early indicator of treatment response.

Heart failure monitoring using the wearable cardioverter defibrillator in patients with newly diagnosed heart failure

Funding Acknowledgements Type of funding sources: None. Background The wearable cardioverter-defibrillator (WCD) can be prescribed in patients with newly diagnosed heart failure. The WCD provides additional heart failure parameters, like heart rate, step count and body position, accessible via remote monitoring. The purpose of this study was to evaluate clinical relevance of additionally recorded data in patients using the WCD. Methods Patients with newly diagnosed heart failure and WCD, an average wear time with at least 20 hours per day and available heart failure parameters were included. The heart failure parameters were provided in 5-minute data intervals. An approximate for the heart rate variability was calculated via the standard deviation of the cycle length of the given heart rate per 5-minute data interval (HRV5). Results 276 patients (68% male) were included between 04/2013 and 12/2017. Mean age was 57.4 ± 15.3 years. 174 patients (63%) suffered from non-ischemic and 102 patients (37%) from ischemic cardiomyopathy. Mean NYHA functional class at prescription was 2.6 ± 0.8. Mean left ventricular ejection fraction (LVEF) was 25.3 ± 8.5%. Mean wear time of the WCD was 111.8 ± 74.5 days. Recorded median heart rate using the WCD was 70.8 (IQR 63.1 - 78.7) beats per minute on the first wear day and 64.5 (IQR 59.7 - 71.3) on the last wear day. Median step count amounted to 4294 (IQR 2283 - 7092) steps on the first wear day compared to 5688 (IQR 3153 - 8263) steps on the last wear day. Median HRV5 was 85.4 (IQR 60.1 - 109.8) ms on the first wear day and 110.4 (IQR 78.6 - 134.9) ms on the last wear day. Between the first and last seven days of usage, median heart rate was significantly reduced (69.5 (IQR 62.0 - 76.8) to 65.9 (IQR 60.4 - 72.2) beats per minute; p &lt; 0.001), while median step counts per day (4657 (IQR 2778 – 6918) to 5562 (IQR 3890 – 8446) steps; p &lt; 0.001) and HRV5 (89.0 (IQR 64.8 - 110.7) to 111.0 (IQR 83.7 - 134.7) ms; p &lt; 0.001) were significantly elevated. A higher delta of heart rate correlated with a higher delta of HRV5A (p &lt; 0,001; rs = 0.488) between the first and last seven days of usage. A higher delta of step counts per day in the first and last seven days correlated with a higher HRV5 (p &lt; 0.001; rs = 0.320). Patients with a higher delta of step count per day (p = 0,005; rs = 0,189) and patients with a higher delta of HRV5 (p = &lt; 0.001; rs = 0.255) showed a higher delta of LVEF measured at prescription and three months follow-up. Conclusion The WCD provides heart failure monitoring using additional heart failure parameters. Patients with newly diagnosed heart failure show a significant difference in heart rate, step count per day and heart rate variability approximate between beginning and end of prescription time. Step count and heart rate variability correlate with LVEF reverse remodeling. Remote monitoring for parameters regarding heart failure might be helpful for close monitoring and further heart failure therapy optimization during WCD wearing.