Remote Technology Monitors Heart Failure Patients
By Mike Bassett
A noninvasive vest can detect a patient's lung fluid levels before he or she becomes symptomatic.
There is little doubt that congestive heart failure is one of the major health burdens confronting the American health system.
According to the Centers for Disease Control and Prevention, about 5.7 million adults in the United States have heart failure. And it is a disease that's becoming increasingly prevalent among older adults.
Other statistics illustrate the seriousness of the condition: About one-half of the people who develop heart failure die within five years of diagnosis, and the cost of heart failure to the nation (taking into account the cost of health care services, medications, and missed work) is estimated at $30.7 billion per year.
One of the problems with the conventional method of managing congestive heart failure is that it's reactive rather than proactive, says Rami Kahwash, MD, a cardiologist and assistant professor of clinical medicine at the Ohio State University Wexner Medical Center, who adds that the typical standard of relying on patients to weigh themselves daily and report symptoms such as ankle swelling or shortness of breath is often inadequate in keeping the condition from taking a serious turn for the worse.
"It's just like crisis management," Kahwash says. "The patient feels the symptoms worsening, goes to the emergency department, gets admitted, and ends up spending a lot of time in the hospital. It's a major health care burden and we need a better way of monitoring those patients before they get to that level."
There are devices on the market that do just that. For example, the CardioMEMS Heart Failure System is a miniature wireless monitoring system that is implanted in the pulmonary artery and can directly measure pulmonary artery pressure. The information is transmitted to a patient's health care providers, allowing them to proactively adjust medications or implement other treatment options that will help the patient avoid hospitalization.
The problem with CardioMEMS is that it is an implant and requires an invasive procedure. "I've got patients who are willing to undergo daily monitoring," says Peter Eckman, MD, heart failure section head at the Minneapolis Heart Institute at Abbott Northwestern Hospital and a researcher for the Minneapolis Heart Institute Foundation. "But they aren't so eager to have a device placed in their bodies."
Now through their institutions, both Kahwash and Eckman are involved in the Sensible Medical Innovations (Noninvasive) Lung fLuid Status Monitor Allows rEducing Readmission Rate of Heart Failure Patients (SMILE) study, a multicenter trial designed to determine whether the use of a wearable device called the SensiVest can reduce the hospital readmission rate of heart failure patients.
The SensiVest, developed by the Israeli company Sensible Medical, uses remote dielectric-sensing technology to quantify lung fluid status. The vest uses radar technology to essentially look through the chest and accurately measure the amount of fluid in the lungs.
"So the vest is basically a noninvasive way of detecting the fluid levels in the lung before a patient becomes symptomatic," Kahwash says.
According to Kahwash, SMILE subjects use the device remotely from their homes once per day. Over the course of about 90 seconds the SensiVest collects lung fluid data and transmits them to a cloud server; they are then made available to investigators through a secure website.
"As physicians monitoring these patients, we are basically able to graph the progression of fluid content in the lung," Kahwash says. "If we see that a patient's trend is headed toward an abnormal fluid level, we can intervene by checking on his status—asking whether he is taking his medications, or whether anything else is going on, and we can increase the water medications.
"So, we can use the vest to guide therapy," he adds. "If we increase the water medications for three days and then see that the patient's line is heading toward a normal range, we can adjust the diuretics and prevent the patient from progressing to the point where they would require hospitalization."
As for the vest itself, it's light—it weighs about 5 lbs—and can be worn over a patient's clothing. Eckman notes that patients might need a little practice learning to put on the vest, and that patients with manual dexterity issues, such as those with arthritis, might run into some challenges, "but for the most part they get the device on pretty quickly."
The multicenter SMILE study is being conducted at 42 different locations across the country and includes about 380 patients; completion is expected by June 2018.
A previous study validating the technology for quantifying lung fluid status was published last year in the International Journal of Cardiology. The investigators, who included William T. Abraham, MD, director of cardiovascular medicine at The Ohio State University Wexner Medical Center and principal investigator of the SMILE study, studied the use of the vest on 50 outpatients, and comparing the results with the patients' historical medical data found that it reduced readmission for heart failure by 87%.
"That was a preliminary trial and included 50 patients only," Kahwash says. "But it showed some promising outcomes, and building on that this trial was designed to be randomized and multicenter and with 380 patients, it is powered enough to show us some clinical evidence that the vest provides a decrease in hospital readmissions."
While no SMILE study data are yet available, Eckman says that his site has enrolled about a dozen patients—with a few already completing their follow-up. "In individual patients the fluid content levels seem to correlate with how they feel," he says. "When the fluid content levels are high, they often feel bad. We give more diuretics, and the fluid level goes down, and they seem to feel better."
While these observations are anecdotal, Eckman says he is encouraged by what he's seen; he is in the process of obtaining a vest that can be used by patients within the clinic to help guide decision making.
"I know there are some centers that have been using it in emergency departments or for hospitalized patients to help decide whether they are still congested or not," he says. "But it hasn't been studied in those populations and remains very investigational."
In the case of his clinic, Eckman suggested it may be used in a case in which the usual data—a patient's history, examination, weight, blood test—still haven't provided enough information to determine whether a patient is full of fluid or not. "So I might use the vest to give me another data point in estimating fluid content," he says. "And if it suggests that fluid content is pretty high, I might give more diuretics. And if it's low, I may back up on the diuretics and focus on other treatments."
As for when the device might be available for daily remote patient monitoring, Eckman suggests it could take some time. "Even if it's proven to be effective, will payers cover it?" he asks. "So it could take two or three years before it's being used routinely and being reimbursed, depending on the trial results."
Kahwash says cardiologists would initially drive use of the device since they follow the vast majority of patients with heart failure. "We will need an infrastructure of staff and physicians who will monitor the data and act on them," he notes. "So initially there will be some phase in which clinics and hospitals will adopt the technology and build the infrastructure needed to monitor patients remotely. That will start with cardiologists and then perhaps migrate to primary care physicians once the technology is more widespread and more people are familiar with it."
The eventual cost of the device is unclear, Kahwash says, "But compared with other technologies being used such as pacemakers, ICDs [implantable cardioverter-defibrillators], or invasive sensors, the vest will be much less expensive because it doesn't involve an implant procedure."
He also points out that another advantage of the vest is that it is reusable, so when a patient is finished with the vest, it can be returned to the provider and used for a different patient.
— Mike Bassett is a freelance writer based in Holliston, Massachusetts.