A satisfactory change in NT-ProBNP plasma levels is defined a priori as either one of the following: a) a decrease in plasma NT-proBNP below 3000 pg/mL (a value which has been associated with a favourable prognosis in our previous study group); b) a decrease > 30% from the first values detected (i.e. those measured 24 to 72 hours before discharge). This percentage is based on previous studies regarding both the prognostic value of serial changes in NT-proBNP levels and their spontaneous week to week variability in clinically stable heart failure patients.