Restoration of intrathoracic impedance at discharge predicts freedom from re-admission for heart failure

Abstract

Background: Intrathoracic impedance decreases when fluid accumulates in the chest and is reduced in patients admitted for acute heart failure (HF). We hypothesized that restoration of impedance at time of discharge from HF hospitalization is associated with reduced risk of HF readmission. Methods: Data from the 836 ICD (20%) or CRT-D (80%) recipients (65 years, 85% male, LVEF 26%, 93% NYHA II/III) enrolled in recent trials (SENSE-HF and DOT-HF) were pooled. Devices automatically performed a daily measurement of impedance (OptiVol®), which was retrieved from device memory. For all HF hospitalizations we determined whether or not the impedance at discharge was restored to the patient's individual long-term reference value (OptiVol Index reaches zero). We compared rate of readmission for HF between cases where impedance had been restored and cases where it had not. Results: A total of 195 HF hospitalizations were reported for 129 patients. Figure A shows Kaplan-Meier estimates for rate of readmission for HF. For 142 HF hospitalizations, the impedance at discharge was available for analysis. For 88, the impedance had been restored to the patient's reference level, whereas for the remaining 54 the impedance continued to be below the reference value. Figure B shows that patients with continued low impedance at discharge had a significantly higher re-admission rate (at 3 months 43.5% versus 24.5%, Hazard Ratio=1.92, p=0.01). ![Figure][1] HF re-admission after discharge Conclusions: In ICD or CRT-D patients who are hospitalized for HF, restoration of transthoracic impedance level above the patient's individual long-term reference value at discharge is associated with lower HF readmission rates. [1]: pending:yes