Heart failure is a syndrome rather than a specific diagnosis. It is the final result of many diseases affecting the heart. Heart failure is usually viewed in terms of heart muscle disease, but other causes of the syndrome include valvular heart disease and chronic arrhythmias. In industrialized societies, the most common cause of heart failure is coronary artery disease. A substantial minority of patients have ‘dilated cardiomyopathy’, in which there is intrinsic heart muscle damage with normal coronary arteries. By definition, the cause of cardiomyopathy is unknown, and this diagnosis should therefore eventually disappear once all the causes of heart muscle dysfunction are identified. The range of causes of specific heart muscle disease is already wide (Figure 1).