The study objective is to measure the value of the third heart sound (S3) for the prediction of recurrent heart failure (HF). For the purpose of this study, a heart failure event will be defined as a hospitalization with a primary diagnosis of heart failure. The main hypothesis of the study is that measurement of S3, using a microelectronic machine microphone positioned in a wearable device (Nanowear Wearable Congestive Heart Failure Management System) near the time of discharge from a hospitalization for heart failure, can predict which patients will be at high risk for a heart failure event, thereby identifying a group in whom increased surveillance and monitoring may decrease hospital readmissions for worsening heart failure.

Heart failure (HF) is a complex clinical syndrome that results from any structural or functional impairment of the heart that affects the filling or ejection of blood in a cardiac cycle. HF manifests clinically as fatigue and dyspnea (shortness of breath). This may in turn result in exercise intolerance and fluid retention. Fluid retention leads to pulmonary congestion and/or peripheral edema [Yancy, 2017]. Cardiac rhythm abnormalities are very common among HF patients. Any new abnormalities that arise in a patient with fluid decompensation prolongs hospitalization as well as increases mortality rates [Lloyd-Jones, 2010; Ross, 2009; Chaudhry, 2015].

Within 5 years of a HF diagnosis, the mortality rate is 50%. The 30 day, 1-year and 5-year mortality rates after HF related hospitalization were 10.4%, 22 % and 42.3 % respectively. Post discharge mortality increased from 4.3% to 6.4% between 1993 and 2005 [Lloyd-Jones, 2010; Ross, 2009]. In 2006, the number of deaths with a mention of HF was as high as it was in 1995. 1 out of every 9 mortalities in the US has HF mentioned as a cause. HF related deaths are approximately 7% of all cardiovascular diseases. In the US, HF related costs exceeded $30 billion in 2013. The average cost per patient for HF related hospitalization was $23,077. Hospitalization after a HF diagnosis happens at least once in 83% of the patients and up to four times in 43% of the patients [Yancy, 2017; Lloyd-Jones, 2010; Ross, 2009].

Heart sounds, and particularly the third heart sound, are well known as specific a very specific clinical signs for heart failure and are associated with worse clinical outcomes. In the context of HF the presence of a pronounced or audible S3 is a specific sign of elevated filling pressures and is suggestive of a restrictive filling pattern with a steep transmitral E-wave [Siejko, 2017]. Recent advances in digital audio technology allow us to not simply assess for the presence or absence of a third heart in objective measures, but also allow us to quantitate it [Buck, 2017; Adamson, 2014; Lloyd, 2019]. Further, recent work has demonstrated that if a frequency range to detect and quantitate the third heart sound is used that extends below the usual range for human hearing, that the third heart sound may be even more predictive of clinical outcomes. The investigators are working with a device manufacturer who have a wearable diagnostic device that includes a directional microelectronic machine microphone that can effectively detect heart sounds. This device will be used to detect and quantitate heart sounds, and specifically the third heart sound, to investigate the prognostic implications of a third heart sound.

Inclusion Criteria:

• Inclusion 1. Subject has provided informed consent
• Inclusion 2. Male or female over the age of 18 years
• Inclusion 3. The patient is either hospitalized with a primary diagnosis of acute heart failure or was discharged with a primary diagnosis of acute heart failure within 2 weeks prior to enrollment.
• Inclusion 4. NYHA functional class II-IV at time of enrollment
• Inclusion 5. Subjects were patients of Penn State Hershey Medical Center (PSHMC), who are/were admitted at PSHMC.

Exclusion Criteria:

• Exclusion 1. Subject unwilling or unable to wear the system for one measurement prior to discharge or within the first two weeks following discharge.
• Exclusion 2. Subjects who are limited by angina.
• Exclusion 3. Severe aortic stenosis.
• Exclusion 4. Subjects who are hemodynamically unstable requiring support with intravenous vasoactive medications or mechanical circulatory support
• Exclusion 5. Symptomatic ventricular arrhythmias within the past 6 months.

Patients, 18 and older, admitted to the hospital with a primary diagnosis of acute heart failure and NYHA class II-IV at time of enrollment.