Cardiac involvement in patients with myotonic dystrophy: Characteristic features of magnetic resonance imaging

Structural alterations of the myocardium, such as fibrosis and fatty infiltration, were observed in post-mortem examinations in patients with myotonic dystrophy, a familial multisystem neuromuscular disease with frequent cardiac involvement. To identify structural and anatomical abnormalities of the heart, 14 patients, aged 45 ± 14 years, belonging to seven families, suffering from myotonic dystrophy were studied. Twelve-lead ECG, high resolution signal-averaged ECG, 24 h Holter monitoring, bidimensional echocardiography and cardiac magnetic resonance (MRI) were performed in all patients. Atrioventricular and/or intraventricular conduction disturbances were present in 11 patients; no major arrhythmias were recorded by Holter monitoring. Ventricular late potentials were present in four patients, absent in eight and not assessed in two (due to left bundle branch block). Echocardiogram showed abnormal findings (left ventricular hypertrophy, mitral valve prolapse, wall motion abnormalities) in eight patients. MRI revealed various cardiac alterations in 11 cases, specifically: left ventricular hypertrophy in seven, right ventricular hypertrophy in two, right ventricular enlargement in six, area of fatty infiltration and fibrosis in the right ventricle in six and in both ventricles in three. Although no clear correlations between the extent of fibro-lipomatous infiltrations and severity of cardiac dysfunction were found, fatty infiltrations were always observed in the most severely diseased patients and were frequently associated with the presence of more advanced conduction disturbances. In conclusion, MRI enabled the detection of structural abnormalities, which previously were observed only in autopsy specimens, and could be a useful investigate method for evaluating the extent of cardiac anatomical alterations in patients with myotonic dystrophy.