Despite its high prevalence and significant rates of associated morbidity and mortality, the syndrome of decompensated heart failure remains poorly defined and vastly understudied. Few high-quality epidemiologic studies, randomized controlled trials, or published guidelines are available to guide the management of this complex disease. In addition, there is no consensus definition of the clinical problem that it presents, no agreed upon nomenclature to describe its clinical features, and no recognized classification scheme for its patient population; all of which has contributed to the lack of therapeutic development in this critical arena of cardiovascular disease. This review outlines the scope of the problem and proposes a system of nomenclature and classification sufficiently simple for general acceptance among clinicians while still encompassing the heterogeneity of the patient population. It also defines the current understanding of strategies for risk stratification in the setting of decompensated heart failure.