Home telemedicine holds the potential to reduce costs and improve outcome among patients with congestive heart failure (CHF). This study aimed to developed a vocal biomarker and evaluate its association with adverse outcome among CHF patients. METHODS: Study cohort included 8,630 patients who were registered to a call center of patients with chronic conditions including CHF. Acoustic features were extracted from 20 seconds of speech for each patient. A biomarker was developed based on a training cohort of non-CHF patients (N=6,646) using machine learning techniques. The biomarker was tested on a mutually exclusive CHF study cohort (N=1,984) and was evaluated as a continuous and dichotomized variable: high (upper quartile) and low. RESULTS: Mean age of the CHF study population was 75±11, 64% were men. During a median follow-up of 18 months (IQR 33-12), 676 (34%) patients died. Kaplan Meier survival analysis showed that the cumulative probability of death among high biomarker group was significantly higher (36%±17% vs. 23%±19%, p<.001). Multivariate Cox regression analysis of the vocal biomarker with adjustment to known predictors of poor survival, demonstrated that each standard deviation increase in the biomarker was associated with a significant 63% increased risk of death during follow-up (95% CI 1.39 - 1.92, p < .0001). The model also demonstrated an independent association of the biomarker with hospitalizations during follow-up (p=.007). CONCLUSIONS: This is the first study to document a relationship between a voice and adverse outcome among CHF patients. The results have important clinical implications for telemedicine and CHF patient care.