Abstract
BACKGROUND
Little is known about the long-term development and outcome of cardiac involvement (CI) in patients with myotonic dystrophy type 1 (MD), Becker muscular dystrophy (BMD), and mitochondrial myopathy (MMP).
OBJECTIVE
To assess the progression of "definite", "possible" or "absent" CI, based on the history, clinical examination, electrocardiography, 24-h ambulatory electrocardiography, and transthoracic echocardiography, over 10 years in MD, BMD, and MMP patients.
METHODS
Included were 13 MD patients, aged 29-60 years, 5 BMD patients, aged 23-68 years, and 9 MMP patients, aged 24-73 years. Main outcome measures were the muscular disability score, the CI-classification, and the sum of abnormality score.
RESULTS
Since seven patients (2 MD, 2 BMD, 3 MMP) died during the observational period and 2 MMP patients refused the 10 year-follow-up, 11 MD, 3 BMD, and 4 MMP patients were actually investigated. At baseline/10 year later CI was "definite" in 12/11, 4/3, 6/4, "possible" in 1/0, 1/0, 3/0, and "absent" in 0/0, 0/0, 1/0 of the MD, BMD and MMP patients respectively. The most frequently abnormal investigations at baseline and follow-up were the history, electrocardiography, and the echocardiography. The mean number of abnormalities per MD, BMD, MMP patient at baseline/10y later was 4.5/5.1, 5.6/7.3, and 4.1/3.5 respectively. Cardiac medication required 25% of the MMP, 27% of the MD, and 100% of the BMD patients.
CONCLUSION
CI becomes "definite" in all patients with MD, BMD, and MMP, but progresses markedly only in BMD patients within 10 years. MD, BMD, or MMP patients should be cardiologically investigated as soon as the neurological diagnosis is established and treated if CI becomes symptomatic, or in case of severe ECG or echocardiographic abnormalities.
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