Heart Failure Monitoring With Eko Electronic Stethoscopes (CardioMEMS)

Heart failure (HF) affects an estimated 6.2 million Americans over the age of 20 and carries a very high healthcare system burden worldwide. Annual costs for HF management in the United States were estimated at $30.7 billion in 2012 and are projected to increase to $68.7 billion by 2030. The primary cost driver for HF management is a high rate of acute decompensation and subsequent hospitalization. The mean per-patient cost of an HF-related hospitalization is estimated to be $14,631.

Among the conditions that the Centers of Medicare and Medicaid Services (CMS) monitors for their Hospital Readmission Reduction Program, HF has the highest median readmission rate at days 1-29 (23%) and days 1-60 (11.4%) postdischarge. The cost burden of HF readmission is $2.7 billion in 2013. A meta-analysis from 2012 estimated that 23.1% of HF readmissions are avoidable, although individual studies ranged from 5% to 79%. Many health plans, including CMS, have focused on interventions that monitor patients for early detection of HF decompensation. Earlier interventions can help care teams prevent avoidable hospitalizations.

Invasive hemodynamic sensor devices have enabled HF care teams to better predict and prevent HF decompensation events, and thus prevent rehospitalizations. One such device is the CardioMEMS pulmonary artery (PA) sensor (Abbott Inc., Atlanta, GA, USA). The CardioMEMS is implanted in a branch of the left PA, allowing for daily measurements of PA pressures. PA pressures are used as a surrogate marker of filling pressure, and rising filling pressures, in turn, are a marker that precedes the exacerbation of HF. The CHAMPIONS trial demonstrated that remote diuretic management using CardioMEMS reduced HF all-cause hospitalizations by 43% and mortality by 57%. Unfortunately, CardioMEMS as an HF solution is invasive, costly (average sales price of $17,750), indicated for a restricted patient population (NYHA class III HF who have been hospitalized within the last year), and has limited reimbursement coverage due to equivocal cost-effectiveness projections.

This has stimulated a search for less expensive, non-invasive sensors that may correlate with fluid status in HF patients. A study in Taiwan demonstrated that outpatient therapy guided by an inpatient device with ECG and sound sensors reduced post-discharge HF utilization by 31% when compared to a control group using symptoms to guide therapy. The LINK-HF study demonstrated that a wearable patch with ECG and sound sensors could predict HF readmissions with a sensitivity of 76% to 88%, a specificity of 85%, and a median lead time of 6.5 days.

Despite these initially promising results, however, these devices have significant disadvantages. The inpatient device used in the Taiwanese study could not be adapted into a portable form factor for outpatient use. Wearable devices can be rigid, uncomfortable, and highly visible, all of which can interfere with patient function and decrease monitoring compliance.