a hospitalization for the primary reason of decompensated HF within the 12 months prior to screening; OR a plasma B-type Natriuretic Peptide (BNP) level ≥ 300 pg/ml or N-terminal prohormone of brain natriuretic peptide (NT-proBNP) ≥1800pg/ml measured during a period of clinical stability in the 3 months prior to screening.