MRI to Evaluate Cardiomyopathies and Inflammatory Cardiac Disease

Background. Earlier classifications of cardiomyopathies described them in terms of their morphologic characteristics (dilated, hypertrophic) or functional consequences (restrictive). The current classification of cardiomyopathies has recently been updated [1] as diseases of the myocardium that are associated with mechanical and/or electrical dysfunction that exhibit inappropriate ventricular hypertrophy or dilatation. The causes are numerous, but an increasing number are being recognized as genetic in etiology. Cardiomyopathies may be primary, i.e. confined to the heart: a) genetic (hypertrophic, arrhythmogenic right ventricular dysplasia, glycogen storage, mitochondrial, ion channel diseases), b) mixed (dilated cardiomyopathy, restrictive cardiomyopathy), or c) acquired (inflammatorymyocarditis, stress, tachycardia induced, infants of insulin dependent mothers). The second category of cardiomyopathies is those that are secondary, as a result of systemic diseases. There are dozens of secondary cardiomyopathies, but examples of those that are more common include infiltrative disorders (e.g. primary or secondary amyloidosis, Gaucher disease), storage disorders (e.g. hemochromatosis, glycogen storage disease) toxic (heavy metals), inflammatory-granulomatous (sarcoidosis). In the case of both primary and secondary cardiomyopathy, MRI is increasingly being applied to both for primary diagnosis as well as for characterization of the extent of disease.