Wearable Device Can Warn of Worsening Heart Failure

A simple, lightweight device worn on the sternum can calculate intracardiac filling pressures, warning that heart failure is worsening, according to a study conducted to determine whether the device can produce the data needed.

The developers are designing the CardioTag device to offer advantages over current implantable hemodynamic monitoring systems in a format amenable to patients and physicians, said Liviu Klein, MD, a cardiologist at the University of California, San Francisco Medical Center, San Francisco, and head of the lab where the research that led to the development of the device was conducted.

The SEISMIC-HF I study assessed the algorithm designed to estimate pulmonary capillary wedge pressure in patients with heart failure from seismocardiography (involving cardiogenic vibrations), photoplethysmography (involving optical pulse waves), and electrocardiography data captured by the CardioTag.

The CardioTag data were compared with pressure tracings from right heart catheterization, the current clinical gold standard, to develop an artificial intelligence model. The estimate of pulmonary capillary wedge pressure was then tested in other patients to ensure its accuracy. Results were very accurate and comparable with those from implantable systems, reported the investigators.

From Implantable to Wearable

Pulmonary artery pressures rise in the weeks before heart failure reaches the point that the patient experiences clinical symptoms and may need to be hospitalized for congestion, said Jessica Golbus, MD, from the Division of Cardiovascular Medicine at the University of Michigan in Ann Arbor, who presented the SEISMIC-HF I results at the American Heart Association Scientific Sessions in Chicago.

If the patient and physician are aware of the increase in pressure, proactive steps can be taken to control heart failure and avoid congestion and hospitalization, she explained.

Implantable devices have been developed to monitor pressures remotely. CardioMEMS, which measures pulmonary artery pressure and is implanted by right heart catheterization, was approved by the US Food and Drug Administration in 2014. And other implantable systems are currently being investigated.

“The clear and obvious advantage of CardioTag is its noninvasive nature,” which is preferred by patients and cardiologists, said Golbus. “As a cardiologist, if I have questions about ambiguity, it takes a couple of weeks to get CardioMEMS placed” because the implantation procedure must be scheduled. In contrast, noninvasive devices such as CardioTag “could be a just-in-time solution if there is clinical ambiguity or equipoise as to what the next steps should be.”

Implantable pulmonary artery pressure sensors are also “very invasive and uncomfortable” for patients, as well as being expensive, Klein pointed out.

CardioTag has other advantages, as well, he said. It provides pulmonary capillary wedge pressure, the gold-standard indicator used in hospitals, whereas pulmonary artery pressure is a surrogate measure. In patients with post-capillary pulmonary hypertension, other measures can lead to an incorrect estimate of pressure and, therefore, inappropriate management.

CardioTag also produces absolute, rather than relative, measures of pressure, unlike some other systems, he added.

Data Needed on Effect on Outcomes

The SEISMIC-HF I study is only the first step, Klein said. “We’ve learned now that we can detect the data.”

However, more research is needed. SEISMIC-HF I was conducted in a single center and limited to patients with heart failure with reduced ejection fraction.

“It’s an early study showing that CardioTag is measuring what it is supposed to,” Golbus said. “It was not designed to evaluate the predictive value or its ability to change outcomes. That’s going to be an important next step before cardiologists feel comfortable using it routinely for their patients,” she said.

“If you don’t act on the data, it’s not going to be helpful,” said Klein.

His next study SEISMIC-HF II will expand the number of patients. SEISMIC-HF I had fewer than 1000 patients. Klein said he also plans to expand to other centers to ensure that CardioTag data “can represent all patients.”

After that study, he is planning a randomized study that will take patients from monitoring to heart failure management, “to truly show benefit” by determining the effect on outcomes such as hospitalization for congestion.