Prediction of readmissions and mortality in patients with heart failure: lessons from the IMPEDANCE-HF extended trial

AimsReadmissions for heart failure (HF) are a major burden. We aimed to assess whether the extent of improvement in pulmonary fluid content (PC) during HF hospitalization evaluated by lung impedance (LI), or indirectly by other clinical and laboratory parameters, predicts readmissions. Methods and resultsThe present study is based on pre-defined secondary analysis of the IMPEDANCE-HF extended trial comprising 266 HF patients at New York Heart Association Class II-IV and left ventricular ejection fraction35% randomized to LI-guided or conventional therapy during long-term follow-up. Lung impedance-guided patients were followed for 5836months and the control patients for 46 +/- 34months (P<0.01) accounting for 253 and 478 HF hospitalizations, respectively (P<0.01). Lung impedance, N-terminal pro-brain natriuretic peptide, weight, radiological score, New York Heart Association class, lung rales, leg oedema, or jugular venous pressure were measured at admission and discharge on each hospitalization in both groups with the difference defined as PC. Average LI-assessed PC was 12.1% vs. 9.2%, and time to HF readmission was 659 vs. 306days in the LI-guided and control groups, respectively (P<0.01). Lung impedance-based PC predicted 30 and 90day HF readmission better than PC assessed by the other variables (P<0.01). The readmission rate for HF was lower if PC>median compared with PCmedian for all parameters evaluated in both study groups with the most pronounced difference predicted by LI (P<0.01). Net reclassification improvement analysis showed that adding LI to the traditional clinical and laboratory parameters improved the predictive power significantly. ConclusionsThe extent of PC improvement, primarily the LI based, during HF-hospitalization, and study group allocation strongly predicted readmission and event-free survival time.