Some implantable cardiac devices capture data that may indicate worsening health in patients with heart failure. Cardiologists are beginning to use that information to identify at-risk patients and intervene before their conditions deteriorate and require hospitalization.
Proactive patient care
More than a million people are hospitalized for heart failure in the U.S. annually at a cost of almost $31 billion, according to the American Heart Association (AHA). Readmissions are high, too: Among Medicare beneficiaries alone, 134,500 patients were readmitted within 30 days for congestive heart failure in 2011, for a bill of $1.7 billion, the Agency for Healthcare Research and Quality calculated. The AHA projected that the cost of caring for patients with heart failure could reach $69.7 billion by 2030.
All these dollar signs prompted the Centers for Medicare & Medicaid Services to make heart failure one of three initial conditions that it would target in a program that now withholds up to 3 percent of Medicare reimbursement to hospitals with higher than expected 30-day readmission rates. That gives hospitals an even greater incentive to monitor heart failure patients for early signs of trouble. The simplest method asks patients to weigh themselves daily to detect signs of fluid retention and report back to physicians.
“If their weight goes up, they call their doctor and take more diuretics,” says E. Kevin Heist, MD, PhD, a cardiac electrophysiologist at Massachusetts General Hospital in Boston. But the approach is often hit or miss. “It is a sensitivity/specificity issue. Either you get so many signals that you stop listening or it is not sensitive enough and lots of people get sick and come in before they have this signal.”
Rather than rely on such blunt instruments, physicians now have an opportunity to get to the heart of the matter, literally. Using implantable devices, they hope to spot signs of early decompensation remotely and intervene before the patient’s condition worsens and he or she needs hospitalization. Two different options have emerged as contenders: standalone devices that are prognostic but not therapeutic and therapeutic devices that could do double duty to predict risk.
“Features embedded in cardiac resynchronization devices [CRT-Ds] and implantable cardioverter-defibrillators [ICDs] have proven to be of some value, particularly in predicting risk,” says William T. Abraham, MD, of the Ohio State University Heart and Vascular Center in Columbus. In one recent study, Abraham and other researchers showed they could stratify patients at risk of heart failure hospitalization using diagnostic notifications in CRT-Ds with defibrillation capability (Heart Lung 2015;44:129-136). “They kind of tell us which patients to worry about more and less but they don’t provide data that are actionable on a day-to-day or week-to-week basis.”
Heist also explored the use of implanted cardiac devices to detect pulmonary congestion in the pivotal study DEFEAT-PE (Detect Fluid Early from Intrathoracic Impedance Monitoring). The study used an algorithm in CRT-Ds and ICDs by St. Jude Medical to monitor changes in intrathoracic impedance, which could be a way to detect pulmonary congestion. “The idea is that as the lung, which is mostly filled with air, begins to fill with fluid, the impedance will drop,” Heist says. That change possibly could be a predictor of heart failure hospitalization.
They concluded that while the algorithm predicted pulmonary congestion events, it failed to find the sweet spot: a low false positive rate along with high sensitivity (Am J Cardiol 2014;114:1249-1256). “It was considered not sufficiently predictive for it to create a red flag that would alert the physician and lead to a change in therapy,” Heist says.
Raising red flags early
After an earlier rejection, the FDA approved CardioMEMS (St. Jude Medical), a miniaturized implantable device for managing heart failure patients, in 2014 based on additional analyses of the CHAMPION trial (CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients). The 550 trial participants all had been rehospitalized for heart failure in the previous 12 months and after enrollment implanted with the CardioMEMS pressure sensor. They then were randomized to be remotely monitored and receive the standard of care or receive standard of care alone.
Physicians in the CardioMEMS group followed a medical treatment