Heart failure is a syndrome characterised by the reduced ability of the heart to pump blood around the body, caused by structural or functional cardiac abnormalities. The condition is characterised by symptoms such as shortness of breath and fatigue, and signs such as fluid retention. Acute heart failure (AHF) refers to the rapid onset of the symptoms and signs of heart failure, often resulting in a hospitalisation, and more common with a first presentation. Chronic heart failure (CHF) describes more stable symptoms, often following effective treatment for acute heart failure, or a more insidious deterioration, where the slow development of symptoms can more easily be missed. People with heart failure are characterised by periods of stability (CHF) when at best they are rendered asymptomatic, and a susceptibility to acute deteriorations or episodes of AHF. Effective treatment of the underlying cause and regular informed review will minimise or even abolish these episodes.