[Cardiac involvement in Steinert's myotonic dystrophy]

Cardiac involvement is described as one of the most frequent multisystemic manifestations of Steinert myotonic dystrophy (DM1). This study was performed to determine the frequency of cardiac abnormalities in Steinert myotonic dystrophy and to decipher the correlation between the severity of cardiac involvement and the degree of neurologic deficit.

Thirty-four DM1 patients 23 men and 11 women, aged 13-61 years (mean 37.3+/-13.2 years) underwent neurological and cardiac evaluations. According to the MDRS scale, 32.5 percent were classified in the second stage, 23 percent in stage 3; 32.5 percent in stage 4 and 12 percent in stage 5. There was a positive correlation between neurological symptoms duration and the MRDS scale. Cardiac involvement was detected in 77.4 percent of patients. Electrocardiographic conduction abnormalities were the most frequent, represented by first-degree atrioventicular block in 64 percent of patients and bundle-branch block in 32 percent. From 5 patients having an invasive electrophysiology testing, subhisien block was observed in 3 patients. We respectively found alterations in systolic and diastolic left ventricular function in 22 percent and 30 percent of patients and a cardiac pacemaker was implanted in 3 patients. The frequency of cardiac manifestations was correlated to the degree of the neurological involvement assisted by MDRS scale, but it seam that the severity of cardiac abnormalities is not correlated to the degree of neurological deficit.

We recommend that patients with DM1 undergo 24-h electrocardiogram monitoring and echocardiography at least yearly. Long-term prospective follow-up is required to determine the prognostic value of the observed abnormalities.