The telemonitoring systems for congestive HF did not yet prove their efficacy despite initial encouraging results. Decongestion is one of the main objectives in Congestive HF, but an appropriate titration of diuretics is warranted, since long-term use of diuretics was consistently found associated with adverse outcomes. The investigators showed (ROSSIGNOL et al., JACC 2011, Circulation 2012) that the aldosterone antagonist eplerenone has diuretic effects, as assessed by an estimated plasma volume depletion, in addition to potassium-sparing properties, independently from renal function variations. These three parameters were independently associated with patient outcomes and may therefore be potential monitoring/and therapeutic targets in patients with congestive HF.

Main objective :

To assess the variations of estimated plasma volume, serum potassium and estimated glomerular filtration rate after an hospitalization for decompensated HF, by using a home-based finger capillary punction for 5 consecutive days per week during the two months postdischarge, using an approved dedicated device (ABOTT iSTAT).

Secondary objectives :

1. to assess the correlations between plasma volume, serum potassium and estimated glomerular filtration rate variations (as measured by Istat, and by a weekly venous punction) and body weight, home blood pressure measurement, dyspnea self assessment variations.
2. bio banking (serum, plasma, urine) for further biomarker studies, one a weekly basis

Inclusion Criteria:

• 18 years old or over
• Patients with heart failure and FE ≤ 45% hospitalized for decompensated heart failure

Exclusion Criteria:

• GFR < 30 ml/min/1.73 m2 as estimated by the abbreviated MDRD formula
• Pregnancy and lactation
• Participation in other investigational trials