Aims: Heart failure (HF) is a major and increasing health problem frequently characterized by signs of congestion. Pulmonary congestion can be difficult to evaluate, stressing the urgent need for new objective, noninvasive approaches. Due to the inverse correlation between tissue hydration and thoracic impedance, bioimpedance monitoring is an effective way for fluid status assessment. In this study, the ability of a wearable bioimpedance sensor to correctly assess longitudinal changes in a patient’s fluid status and the influence of these bioimpedance changes on clinical outcome were studied. Methods and results: A wearable bioimpedance device from Holst center (Imec, Eindhoven, The Netherlands) was used for thoracic impedance measurements. Thirty-six patients admitted to the emergency ward with signs of acute decompensated HF were included. Changes in the resistance at 80 kHz (R80kHz) were used for analyses and patients’ fluid balance was taken as a reference measure. The wearable bioimpedance sensor showed the expected inverse relation with fluid balance and a moderate negative correlation was found (r= -0.51, p < 0.001). Patients were divided in two groups, i.e. those with a relative increase in R80kHz and those with a relative decrease in R80kHz from admission to last available measurement. For patients with a relative increase in R80kHz, the highest change in R80kHz was observed on the first day. Finally, a significant survival benefit was observed for patients showing an increase in R80kHz (88% versus 50%, p=0.005). Conclusion: The current study shows the ability of a novel wearable bioimpedance device to track longitudinal changes in fluid status. More interestingly, a significant survival benefit was observed for patients who showed an increase in bioimpedance.