Introduction: Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystemic disease with frequent cardiac involvement that may cause sudden death. This study was performed to determine the various cardiac manifestations in DM1, their frequency and the relevance of cardiac electrophysiological study in this disease.
Methods: Ten patients with DM1, five men and five women, mean age 44.3+/-7.8 years underwent neurological and cardiac assessments.
Results: The most frequent electrocardiographic findings were conduction abnormalities, essentially by intraventricular conduction defects (eight out of ten cases) such as bundle branch or fascicular blocks. Echocardiography showed alterations in systolic left ventricular function in two cases. Invasive electrophysiology testing showed sub-hisien block in three patients, requiring cardiac pacemaker implantation. These three patients had normal duration of PR interval and normal width of QRS complex.
Conclusions: We recommend that all patients with DM1 should undergo cardiac investigation to detect subclinical cardiac involvement.