[Frequency of electrocardiographic changes in patients with myotonic dystrophy].

Cardiac abnormalities are frequently associated with myotonic dystrophy (MD), and electrocardiographic (ECG) changes are not rare in these patients. The most common ECG abnormalities are PQ or QT interval prolongation, low P wave amplitude, ST elevation or depression, negative T waves, conduction and rhythm abnormalities. We analysed ECG changes in 42 patients with MD. ECG abnormalities were obvious in 24 (57%) patients. The most prevalent ECG changes were sinus bradycardia and low P wave amplitude, occurring in 23 (55%) patients. Nineteen (45%) patients had QTc prolongation. PQ prolongation occurred in 16 (38%) patients, abnormal Q waves in 9 (21%), intraventricular conduction defects in 7 (16%) and QRS prolongation or T wave changes in 4 (9%) patients. We found no ST alterations. ECG changes were more frequent in patients with severe disease, but it was not statistically significant. There was no correlation between age and ECG abnormalities in our patients.