Early detection of cardiomyopathy in Duchenne muscular dystrophy, is there a role for MRI?

Muscular dystrophies are progressive myopathic disorders resulting from defects in a number of genes required for normal muscle function [1]. Duchenne muscular dystrophy is caused by a defective gene located on the X chromosome, that is responsible for the production of dystrophin [2] and is related to other inherited myopathies like Emery–Dreifuss muscular dystrophy, Becker muscular dystrophy, limb-girdle muscular dystrophies, fascioscapulohumeral muscular dystrophy and myotonic dystrophy. Duchenne muscular dystrophy has a recessive inheritance. The disease is clinically associated with muscle fiber degeneration. The incidence is one in 3,500 live male births, with a prevalence of 3 per 100,000 [3]. The clinical onset of weakness usually occurs between 2 and 3 years of age [4]. One of the major complications of Duchenne muscular dystrophy is a dilated cardiomyopathy. The main cardiac expression of the disease is extensive fibrosis of the posterobasal and lateral left ventricular wall. In patients with Duchenne muscular dystrophy, the incidence of the cardiomyopathy increases from zero under the age of 10, to one-third at the age of 14 years to one half at the age of 18 years and nearly 98% in patients over 18 years [5]. The incidence of cardiac failure in female carriers is reported to be 10% even in the absence of skeletal muscle involvement [6]. However, in these females carriers, life expectancy is not affected by the presence of the abnormal gen [7]. The cardiomyopathy can be detected by an abnormal ECG characterized by tall right precordial R waves with an increased R/S ratio and deep Q waves in the lateral leads and by echocardiography showing localised lateral thinning and akinesia and noncompaction of the endocardium ultimately progressing in a dilated cardiomyopathy [8–10]. For early and appropriate detection of cardiac involvement of muscular dystrophy, a recent workshop on the management of cardiac involvement in muscular dystrophy gave the following recommendations: