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Lung impedance-guided preemptive treatment for chronic heart failure (CHF) appears to reduce CHF-related hospitalizations and HF incidence and mortality, according to results of the IMPEDANCE-HF clinical trial, presented at the 2016 American College of Cardiology Scientific Sessions & Expo (ACC), and simultaneously published in the Journal of the American College of Cardiology.
Michael Shochat, MD of the Heart Institute, Hillel Yaffe Medical Center in Hadera, Israel, presented the study findings at the ACC meeting in Chicago.
Dr Shochat and colleagues set out to test the hypothesis that lung impedance-guided treatment would reduce acute HF (AHF) hospitalizations. “The main reason for AHF hospitalization is lung fluid overload,” they explained in their publication. “Therefore the idea to detect lung fluid overload non-invasively at an early stage is attractive.”
They used a “highly sensitive device” (Edema Guard Monitor; RSMM; Jerusalem, Israel) that was able to detect small changes in lung fluid, enabling “preemptive treatment at an early and critical stage.”
IMPEDANCE-HF was a single-blind, 2-center trial that included 256 patients with CHF and left ventricular ejection fraction ≤35% in the New York Heart Association (NYHA) class II-IV. Prior to enrollment, these patients were admitted for acute HF within the previous 12 months.
Healthy volunteers (n=30) had measurements of lung impedance taken between 15 and 30 times during a 12-month period in order to assess the physiological day-to-day variability. Researchers found that lung impedance deviates in normal healthy individuals by ±2.1% on a daily basis.
The patients were randomly assigned by a 1:1 ratio to either clinical assessment management with noninvasive lung impedance (monitored group) or management without lung impedance (control group).
The primary efficacy end point was AHF hospitalizations and the secondary end points were all-cause hospitalizations and mortality. Patients were followed up for at least 12 months.
During the first year, there were 67 AHF hospitalizations in the monitored group compared with 158 in the control group (P<.001). During the follow-up period, 211 AHF hospitalizations occurred in the monitored group and 386 in the control group (P=.01).
Forty-two deaths occurred in the monitoring group and 59 in the control group (hazard ratio [HR]: 0.52; 95% confidence interval [CI]: 0.35-0.78; P=.002). Of these deaths, 13 and 31 of them were related to HF (HR: 0.30; 95% CI: 0.15-0.58; P<.001) in the monitored and control groups, respectively. With regard to non-cardiovascular hospitalizations, there was no difference between groups (P=.82).
Investigators stratified the annual rate of HF hospitalizations by NYHA class to determine whether the effect of lung impedance monitoring was NYHA class-dependent. In the monitored group, there were 61, 38, and 29 patients classified as NYHA II, III, and IV, and 60, 39, and 29 patients in the control group.
For NYHA class II, the hospitalization rate was 0.36 vs 0.94 (HR: 0.47; 95% CI: 0.36-0.66; P<.001) for monitored vs control patients. For NYHA class III, the hospitalization rate was 0.74 vs 1.81 (HR: 0.74; 95% CI: 0.55-0.98; P=.04) for monitored and control groups. Finally, NYHA class IV, the hospitalization rate was 1.17 vs 2.16 (HR: 0.52; 95% CI: 0.37-0.72; P<.001) for monitored and control groups. Given these results, assessment of patient congestion is most likely more accurate via device than clinical assessment of NYHA class (based mostly on patient self-assessment.)
For hospitalizations specifically related to AHF, the change in lung impedance ratio (LIR) values at 1 month prior, during admission, and after hospitalization demonstrate a progressive decline 3 weeks before hospitalization in both study groups.
“Importantly, we have confirmed our previous finding since there were no AHF hospitalizations if change in LIR decreased by less than 24% from BLI [baseline lung impedance],” the researchers wrote. “Therapy during hospitalizations alleviated congestion substantially in both study groups as change in LIR increased by 21% in the monitored group…and by 20% in the control group.”
Dr Shochat and colleagues concluded that lung impedance monitoring “should be considered in patients with CHF with reduced LV [left ventricular] function to improve outcomes.”
Disclosures: Dr Shochat is a co-founder and member of the board of directors of the RSMM Company, manufacturer of the devices used in the IMPEDANCE-HF trial.
References
- Shochat MK, Shotan A, Blondheim DS, et al. Non-invasive lung IMPEDANCE-guided preemptive treatment in chronic heart failure patients: a randomized controlled trial (IMEPEDANCE-HF) trial. J Am Coll Cardiol. 2016; 67(13_S):1278-1278. doi: 10.1016/S0735-1097(16)31279-7.
- Shochat MK, Shotan A, Shochat I, et al. LBCT V. Non-invasive lung IMPEDANCE-guided preemptive treatment in chronic heart failure patients: a randomized controlled trial (IMPEDANCE-HF trial.) Presented at the 65th Annual American College of Cardiology Scientific Sessions & Expo. April 2-4, 2016; Chicago, IL.
