Monitoring intrathoracic fluid with ICDs predicts subsequent heart failure-related adverse events according to the results of a late breaking clinical trial presented at 12th Annual Scientific Meeting of the Heart Failure Society of America (HFSA) in Toronto.

The findings of the Multi-Site Program to Access and Review Trending Information and Evaluate Correlation to Symptoms in Patients with Heart Failure (PARTNERS-HF) study was presented by Dr. David Whellan, who is an Associate Professor of Medicine, Jefferson Heart Institute, Thomas Jefferson University, Philadelphia, PA. This clinical trial was designed to determine if using intrathoracic-impedance monitoring, which works by measuring electrical pulses across the thoracic cavity to assess fluid in the chest, could identify patients with worsening heart failure.

Researchers followed 769 heart-failure patients with NYHA class 3 or 4 and left ventricular ejection fractions <35% who were treated with cardiac resynchronization devices with defibrillators (CRT-D).

Patients with a fluid index that crossed a predefined threshold in the 21-day evaluation period were twice as likely as those who did not cross the impedance threshold to have a subsequent heart-failure event. In a second analysis, patients crossing the threshold during a rolling a seven-day evaluation window were 3.5 times more likely to have a subsequent heart-failure event. Fluid indices crossing the predefined threshold significantly increased the risk of subsequent decompensation, shortness of breath, peripheral edema, and fatigue, suggesting impedance data can help stratify patients at risk for worsening heart failure.

"This finding could be important to help us better understand how body functions (i.e., excess fluid) effect the progression of heart failure," said Dr. Barry Greenberg, HFSA President, and Professor of Medicine, and Director, Advanced Heart Failure Treatment Program, University of California, San Diego. "Diagnostic measures that would lead to early detection of changes in various parameters could ultimately allow us to intervene at an early time and thus prevent cardiac events from occurring."

Dr. Whellan explained that the trial observed how well the diagnostic parameters predicted the incidence of clinical events. "We now have this continuous diagnostic data available for patients during in-clinic visits as well as a remote follow up over the Internet. This trial found that patients with a high intrathoric fluid were about three times more likely to have a subsequent heart failure event, independent of other clinical variables."