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[Cardiomyopathy in Becker muscular dystrophy]
C Sakata1, H Yamada, N Sunohara
1Department of Neurology, National Center of Neurology and Psychiatry.
Insights
Becker muscular dystrophy (BMD) patients often develop heart problems like dilated cardiomyopathy, regardless of muscle weakness severity. Early cardiac monitoring is crucial for all BMD patients due to poor prognosis.
Area of Science:
- Cardiology
- Neurology
- Genetics
Context:
- Becker muscular dystrophy (BMD) is a genetic neuromuscular disorder.
- Cardiac involvement, specifically dilated cardiomyopathy (DCM), is a known complication.
- The relationship between cardiac and muscular symptoms in BMD requires further elucidation.
Purpose:
- To investigate the clinical features and prognosis of cardiac involvement in Becker muscular dystrophy.
- To compare patients with and without dilated cardiomyopathy within a BMD cohort.
- To determine if clinical parameters predict cardiac complications in BMD.
Summary:
- Three of six Becker muscular dystrophy patients presented with dilated cardiomyopathy.
- No significant differences in age of onset, disease duration, muscle weakness severity, or dystrophin levels were observed between DCM and non-DCM groups.
- Cardiac symptoms in a larger cohort (14 patients) appeared between ages 4-41 (average 17.1), with no correlation to muscle weakness severity.
Impact:
- Becker muscular dystrophy patients with cardiomyopathy have a poor prognosis, with heart failure and cardiac transplantation being significant outcomes.
- Myocardial involvement in BMD is not directly related to the clinical severity or duration of muscle disease.
- Routine cardiac function monitoring is essential for all Becker muscular dystrophy patients, even those with mild muscle weakness, to detect early signs of cardiomyopathy.
Abstract:
In 6 patients with dystrophin-verified Becker muscular dystrophy (BMD), 3 patients had dilated cardiomyopathy (DCM group). The other 3 patients (non-DCM group) also had ECG abnormalities including incomplete right bundle branch block, left ventricular enlargement and intraventricular conduction defect. Between DCM and non-DCM group, there was no prominent difference in ages at onset, mean duration and severity of muscular weakness. Serum CK levels, and molecular weight and amount of dystrophin also showed no significant difference between two groups. On reviewing 14 BMD patients, including 3 present patients with cardiomyopathy, the cardiac symptoms appeared from 4 to 41 years, averaging 17.1 years of age. The mean duration of muscle symptoms was 9 years, ranging from 0 to 33 years. There was no correlation between severity of muscle weakness and cardiomyopathy. Six patients died of heart failure and 3 received cardiac transplantation. Thus there was no characteristic clinical feature in BMD patients with cardiomyopathy except for very poor prognosis. Since the myocardial involvement is not related with clinical severity and duration of the disease, careful observation for cardiac function should be carried out in all BMD patients even in the early stage of muscle weakness.