On some cardiological aspects of Steinert's disease (myotonic dystrophy)

The authors investigated 10 ambulant patients with myotonic dystrophy, under 40 years of age (mean 22.3 years) and free of subjective heart complaints. Not only Ecg alterations but also kinetocardiographic changes and anomalies of the systolic intervals were rarer and milder than those found in patients with other neuromyopathies, namely Friedreich's disease and Duchenne's disease. This observation suggests that, at least in older patients, not all the cardiac alterations usually attributed to myotonic dystrophy are really imputable to the disease. On the other hand, the observed echocardiographic alterations (reduction of per cent systolic-diastolic variation of internal diameter of the left ventricle and/or the ejection fraction) apparently indicate an early tendency to modification of left ventricular function in patients with myotonic dystrophy. Since other authors have found cardiac anomalies in this disease before the onset of any neurological manifestations, the possibility emerges that some cases of myocardial disease interpreted as "primitive" might in reality be secondary to undetected myopathy.