Cardiac resynchronization therapy in a case of myotonic dystrophy (Steinert's disease) and dilated cardiomyopathy.

Steinert's disease (Dystrophia myotonica type 1) is an autosomal dominant neuromuscular disease characterized by myotonia, muscle weakness, frontal balding, cataracts, cardiac conduction abnormalities, especially long PR interval and wide QRS complex. Although subclinical mild myocardial dysfunction may be detected in this syndrome, overt myocardial dysfunction with heart failure called as "myotonic heart disease" is not frequent. Cardiac resynchronization therapy is an effective treatment modality to improve morbidity and mortality in patients with intraventricular conduction delay and congestive heart failure. We report improvement of cardiac dyssynchrony and symptoms of heart failure with biventricular pacing in a 37-year-old male patient with overt myotonic heart disease, PR segment prolongation, and complete left bundle branch block.