DALLAS — An automated system may be able to monitor intracardiac pressures and alert physicians when the pattern suggests impending decompensation, based on a pilot analysis of data collected on 95 acute heart failure events.
The system continuously scans data and notifies the physician when pressures change meaningfully, Dr. Philip B. Adamson said at the annual scientific sessions of the American Heart Association. The scanning system developed by Dr. Adamson and his associates monitors changes in intracardiac pressures measured by the implanted Chronicle device, which is made by Medtronic Inc. and is under review by the Food and Drug Administration. Dr. Adamson has served as a consultant to Medtronic.
“The key to using this data is to learn the right pressure for each patient,” said Dr. Adamson, director of the Heart Failure Institute at the Oklahoma Heart Hospital in Oklahoma City.
The device was tested on 274 patients with advanced heart failure in the Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure (COMPASS-HF) trial. Intracardiac pressure data collected by the device was used by physicians to manage 134 patients. The collected data was not used to manage 140 controls.
Data collected for 56 of the control patients was used in Dr. Adamson's analysis. These 56 patients had a total of 95 episodes of acute decompensation that resulted in either a hospital admission or treatment in an emergency department or urgent-care clinic.
The automated data monitoring focused on the estimated pulmonary-artery diastolic pressure. A rule about changes in this pressure was devised using data gathered before 42 of the 95 events. The pattern was that events usually occurred about 2 weeks after a significant rise in pulmonary-artery diastolic pressure. This criterion identified 35 (83%) of the 42 events, Dr. Adamson said.
This criterion was then applied on a test basis to the remaining 53 clinical events used in the analysis. A 7-day average of prior pulmonary-artery diastolic pressures was calculated for each patient every day, and this reference value was applied to each day's new pressure readings. Small changes in pulmonary-artery pressure over a long period, or large changes in pressure over a short period were considered flags of an impending event.
This method identified 43 (81%) of the 53 heart failure events included in the test. The impending events were flagged an average of 26 days before the events actually occurred.