Acute heart failure encompasses a syndrome that results from a systemic volume overload and congestion. By definition, it can be a first-time diagnosis (de novo heart failure) or an acute deterioration of a preexisting left or right ventricular structural or functional dysfunction. The patient population presents itself very heterogeneously, and consequently, there is also a significant heterogeneity regarding the underlying cardiac pathology leading to the acute presentation. Ultimately, left ventricular dysfunction leads to increased preload and afterload with resulting pulmonary congestion. Due to forward failure (hypoperfusion) and systemic congestion (backward failure), there can be an impairment of end-organ function, which in its maximum form corresponds to cardiogenic shock. Currently, therapeutic approaches primarily focus on correcting the underlying cardiac dysfunction, reducing volume overload (decongestion), and hemodynamic stabilization with inotropic drugs in the case of signs of a hypoperfusion syndrome. Despite numerous new therapeutic approaches within the last decades, the empirical study situation is currently significantly less broad than for chronic heart failure, which is also reflected in the still high 1-year mortality of about 20–30%.