Iron Overload Cardiomyopathy in Clinical Practice
Originally published15 Nov 2011;124:2253–2263
The cardiomyopathies are heart muscle diseases of primary or secondary origin. Primary cardiomyopathies are often of unknown cause, hence their treatment is limited to general heart failure management. In secondary cardiomyopathies, in contrast, the identification of the underlying cause allows for a more specific, hence effective, approach that, when applied early, may prevent the development of heart failure.
The term iron overload cardiomyopathy (IOC) recently has been introduced to describe a secondary form of cardiomyopathy resulting from the accumulation of iron in the myocardium mainly because of genetically determined disorders of iron metabolism or multiple transfusions.1,2 This condition, although previously overlooked, has lately attracted the attention of investigators because iron overload is, on one hand, a frequently encountered condition, especially in association with certain hematologic conditions, and on the other hand, its accurate identification and effective management have now become possible.
IOC has been recently described as a dilated cardiomyopathy, characterized by left ventricular (LV) remodeling with chamber dilatation and reduced LV ejection fraction (LVEF).1 However, primary hemochromatosis, a genetically determined condition leading to iron overload, is classically categorized as an infiltrative cause of restrictive cardiomyopathy.3 Moreover, secondary hemochromatosis may lead to severe diastolic LV dysfunction in the early stages of the disease, before LVEF is affected.4,5 In the present review, we describe the forms, pathophysiology, and phenotypic expression of IOC, focusing on ventricular geometry and function and describing the early diastolic abnormalities that lead ultimately to heart muscle dysfunction and heart failure. The clinical implications of the condition are also discussed.