The term “cardiomyopathy” refers to specific diseases affecting the myocardium which generally lead to clinical manifestations of heart failure, including exercise intolerance, dyspnoea, and fluid retention. The causes of cardiomyopathy can be broadly divided into two categories, ischaemic and non-ischaemic. In ischaemic cardiomyopathy, ventricular dysfunction is a consequence of myocardial ischaemia and infarction related to coronary arteriosclerosis, while there are many potential causes of non-ischaemic cardiomyopathy (NICM), including haemodynamic pathology, infection, immunologic abnormalities, toxic injury, or genetic factors. Determining the prevalence of NICM is made difficult by the heterogeneity in definitions and diagnostic criteria, selection bias in populations studied, and geographic variation. Many epidemiological and clinical studies simply classify patients as having NICM if heart failure is present but there is no clinical or electrocardiographic evidence of coronary disease. In addition, there are clear differences in population characteristics between community-based studies versus analyses of populations from referral centres. Finally, there appears to be geographic variation in the prevalence of specific aetiologies of NICM. Estimates of the prevalence of NICM range from 2–15% in community or hospital settings, and up to 50% in large clinical trials.¹

Although the causes of NICM are many and varied, they generally culminate in a final common pathway of myocardial injury leading to ventricular dysfunction and clinical heart failure. In many cases of NICM a specific aetiology is never identified, or if one is, then frequently no aetiology-specific treatment is available; thus, treatment of NICM frequently includes standard management for systolic heart failure. While a minority of cardiomyopathies manifest with preserved systolic function, this article specifically reviews management of NICM manifesting with left ventricular (LV) systolic dysfunction.

AETIOLOGY

Many types of NICM are not treatable with specific therapies beyond those used for heart failure in general. A significant proportion of patients with NICM have idiopathic dilated …