Atrial Pressure Monitors May Reduce HF Hospitalizations


SNOWMASS, COLO. — Implantable left atrial pressure sensors may provide a breakthrough in the outpatient management of heart failure by identifying impending acute decompensations hours to days before symptom onset, said Dr. James S. Forrester at a conference sponsored by the Society for Cardiovascular Angiography and Interventions.

“I believe that by using implanted hemodynamic sensors, the mechanisms responsible for acute decompensation of heart failure can be defined in the vast majority of patients, and that the physician can prevent these episodes using preplanned strategies. Implanted sensors will be able to decrease hospitalization, reduce progression of heart failure, and increase quality of life in these patients,” said Dr. Forrester, professor of cardiovascular research at Cedars-Sinai Medical Center and professor of medicine at the University of California, both in Los Angeles.

Heart failure (HF) is “arguably the biggest problem in all of health care,” he said. It already tops the list in terms of Medicare hospitalization costs, a situation that will only worsen with the aging of the population.

Dr. Gregg C. Fonarow of the University of California, Los Angeles, showed in previous research that HF patients with a well-controlled left atrial pressure (LAP) of 16 mm Hg or less at hospital discharge had a 46% lower mortality and 85% reduction in rehospitalizations, compared with those with a higher LAP.

By contrast, cardiac output, right atrial or pulmonary artery pressures, and systemic vascular resistance each failed to predict outcomes.

“Increased left atrial pressure is associated with increased acute and long-term mortality and is the real driver of heart failure rehospitalization,” Dr. Forrester stressed.

There are two investigational implanted devices that are being developed for LAP assessment. The first is the Medtronic Chronicle, which is under review by the Food and Drug Administration for possible marketing approval. Dr. Forrester is involved in studies of a second device, the Savacor HeartPOD System, which was invented by colleagues at Cedars-Sinai.

The HeartPOD consists of a pressure monitor placed in the left atrium via transseptal catheterization and a handheld device that can convey information to the patient.

The device beeps at certain times during the day to remind the patient to record the LAP. It also stores the LAP waveform and gives the patient instructions that have been previously entered into the device by the physician.

The instructions could be about changes in medications and activity in response to different LAP levels, and, if warranted, a directive to contact the physician.

To date, the HeartPOD has been implanted in 18 heart failure patients, with a collective 76 months of follow-up. Although that is insufficient clinical experience from which to draw conclusions, the pilot study results are encouraging.

The number of total hospitalizations was significantly lower, compared with an equal period in the previous year, and there have been no unplanned HF hospitalizations or clinic visits since the monitors were activated, Dr. Forrester said.

The early experience with the HeartPOD has already yielded fascinating new insights into HF physiology. For example, huge fluctuations in LAP occur during the course of a day, most of which are asymptomatic.

But as LAP goes up, increasingly large V-wave peaks appear, which is evidence the patient is developing mitral insufficiency. And when LAP increases to a certain level, a patient often becomes dyspneic. Some patients exhibit diurnal variation in LAP, with the peak coming in the early morning. These LAP variations can be attenuated—and dyspnea often prevented—by preemptive changes in medications, according to Dr. Forrester.

The Medtronic device was assessed in the previously reported 274-patient Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) randomized trial.

In that study, physicians used data from patients' implantable monitors to guide HF therapy.

The patients had a 22% reduction in the primary study end point—the 6-month combined incidence of HF-related hospitalizations and emergency department and urgent-care visits— compared with controls.

However, this finding was not statistically significant, probably because the trial was underpowered, Dr. Forrester said.

But he noted that the Chronicle's sensor, which is placed near the right ventricular outflow tract and infers LAP indirectly from a measurement of pulmonary artery end diastolic pressure, could sometimes give inaccurate LAP results.

Dr. Forrester is chair of the scientific advisory committee for Savacor, a Research!America company. He holds a significant financial interest in the company.

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