Application of a novel non-invasive device, which provides a more accurate estimate of lung impedance as a measure of lung fluid content in patients with chronic symptomatic heart failure (HF) and reduced left ventricular ejection fraction, may aid in reducing hospitalizations for worsening HF according to a study presented today at a Late Breaking Trial Presentation during the American College of Cardiology Scientific Sessions 2016 and simultaneously published in the Journal of Cardiac Failure.
Interventions to reduce hospitalizations for worsening HF continue to be one of the most important areas of investigation as high readmission rates for HF continue to drive health care resource utilization and financial penalties for hospitals. One of the most promising approaches is application of technologies that allow for detection of hemodynamic alterations signaling impending decompensation allowing for the implementation of early patient-centered interventions.
The current study by Shochat et al evaluated a novel non-invasive device which provides a more accurate estimate of lung impedance as a method to detect changes lung fluid content. The novel device allows for subtraction of the contribution of the chest wall from overall transthoracic impedance, providing a more accurate measurement of lung impedance. The Non-invasive Lung IMPEDANCE-guided Preemptive Treatment in Patients with Chronic Heart Failure (IMPEDANCE-HF, NCT01315223) trial randomized 256 chronic symptomatic HF patients (New York Heart Association functional classification II-IV, left ventricular ejection fraction ≤35%, and previous HF hospitalization within 12 months) in a single-blind fashion to a control group (clinical assessment) or a monitored group (lung impedance assisted). Patients were followed in clinic for at least 12 months, with lung impedance measured at each visit. The primary outcome of HF-related hospitalizations was significantly reduced in the monitored group compared to the control group during the first year [67 monitored group vs. 159 control group, HR 0.51 (95% CI 0.38-0.68), p<0.001], and for the entire duration of the study [211 monitored group vs. 386 control group, HR 0.63 (0.53-0.735), p<0.0001].
Importantly, decreases in lung impedance appeared to precede hospitalizations. Medication regimen modifications were significantly more frequent in the monitored group. All-cause mortality was also lower in the monitored group. The authors concluded the addition of non-invasive lung impedance monitoring to guide titration of medical therapy for HFrEF patients in an outpatient clinic significantly reduced the incidence of HF-hospitalizations.
“The study by Shochat et al. adds to the mounting evidence that early detection of hemodynamic changes provides additive value above routine clinical assessment in the outpatient setting for the prevention of heart failure decompensations necessitating hospitalization”, said Dr. Tien Ng, PharmD, Associate Editor of the JCF. “The potential advantages and disadvantages of the novel non-invasive device algorithm used in IMPEDANCE-HF needs to be explored further, and compared to other implantable hemodynamic monitoring devices. As a corollary finding, it also re-emphasizes that medical optimization is an ongoing process even in stable patients with chronic HF, and remains one of the most effective approaches to reducing HF morbidity and mortality.”
The study was conducted solely in patients with HF and reduced ejection fraction, and the value in different HF populations remains to be determined. Additional limitations were the exclusion of patients with chronic kidney disease in whom additional data on fluid status may be of even greater value, and the single-blind design which may have influenced hospitalization decisions.
About the Journal of Cardiac Failure, Heart Failure Society of America and Japanese Heart Failure Society
The Journal of Cardiac Failure is associated with the Heart Failure Society of America and the Japanese Heart Failure Society. JCF publishes original, peer-reviewed communications of scientific excellence and review articles on clinical research, basic human studies, animal studies, and bench research with potential clinical applications to heart failure - pathogenesis, etiology, epidemiology, pathophysiological mechanisms, assessment, prevention, and treatment.