Acute heart failure syndromes (AHFS) enclose a broad spectrum of conditions with different clinical presentations, heart failure history, pathophysiology, prognosis and treatment. AHFS represent a major public health problem because of their high prevalence, high rates of mortality and readmissions and significant healthcare costs, and a therapeutic challenge for the clinicians because management strategies vary markedly. Traditionally used drugs for the treatment of AHFS, including diuretics, vasodilators and positive inotropics, improve clinical signs and symptoms as well as hemodynamics, but present important limitations, as they fail to reduce and may even increase in-hospital and postdischarge mortality, especially in patients with coronary artery disease. Thus, we need new pharmacological agents to not only improve signs and symptoms and cardiac performance, but also improve both short- and long-term outcomes (hospitalizations/survival). In the last decade, significant efforts have been made to identify new therapeutic targets involved in the genesis/progression of AHFS and to develop new therapeutic strategies that may safely improve outcomes. As a result, several new families of drugs have been developed and are currently studied in experimental models and in Phase II and III clinical trials, in an attempt to define their efficacy and safety profiles as well as their precise role in the treatment of AHFS patients. This review firstly analyzes the main clinical applications and limitations of conventional drugs, and then focuses on the mechanisms of action and effects of recently approved drugs and of new investigational agents on signs, symptoms, hemodynamics and outcomes in AHFS patients.