CARDIAC INVOLVEMENT IN BECKER MUSCULAR-DYSTROPHY

Objectives. The purpose of this study was to assess the incidence of m yocardial involvement and the relation of cardiac disease to the molec ular defect at the deoxyribonucleic acid (DNA) or protein level in Bec ker muscular dystrophy. Background. Dystrophin gene mutations produce clinical manifestations of disease in the heart and skeletal muscle of patients with Becker muscular dystrophy. Methods. Thirty-one patients underwent electrocardiographic and echocardiographic examination and 24-h Holter monitoring. The diagnosis was established by neurologic ex amination, dystrophin immunohistochemical assays or Western blot on mu scle biopsy, or both, and DNA analysis. Results. Electrocardiographic and echocardiographic findings were abnormal in 68% and 62% of the pat ients, respectively. Right ventricular involvement was detected in 52% . Left ventricular impairment was observed either as an isolated pheno menon (10%) or in association with right ventricular dysfunction (29%) . Right ventricular disease was manifested in the teenagers, and an im pairment of the left ventricle was observed in older patients. Right v entricular end-diastolic volumes were significantly increased compared with those in a control group. The left ventricular ejection fraction was significantly lower in older patients than in control subjects or younger patients. Life-threatening ventricular arrhythmias were detec ted in four patients. No correlations were found between skeletal musc le disease, cardiac involvement and dystrophin abnormalities. In our p atients, exon 49 deletion was invariably associated with cardiac invol vement. Exon 48 deletion was associated with cardiac disease in all bu t two patients. Conclusions. The cardiac manifestation of Becker muscu lar dystrophy is characterized by early right ventricular involvement associated or not with left ventricular impairment. Exon 49, deletion is associated with cardiac disease.