RESUMO
OBJECTIVE: To assess the progression of cardiac involvement (CI), defined as 'definite', 'possible' or 'absent', based on history, clinical examination, electrocardiography, 24 h ambulatory electrocardiography and transthoracic echocardiography in patients with myotonic dystrophy (MD), Becker muscular dystrophy (BMD) and mitochondrial myopathy (MMP) over five years. DESIGN: An investigational, follow-up study. SETTING: A neurological and cardiological department in Austria. PATIENTS: Thirteen patients aged 29 to 60 years with MD, five patients aged 23 to 68 years with BMD and 10 patients aged 24 to 73 years with MMP. MAIN OUTCOME MEASURES: Muscular disability score, CI score and sum of abnormality score. RESULTS: Five patients (two with MD, one with BMD, two with MMP) died during the observational period, one died presumably from rhythm abnormalities. One patient refused to join the follow-up. At baseline/five years later, CI was 'definite' in 12/10, four/four and six/three; 'possible' in one/one, one/zero and three/four; and 'absent' in zero/zero, zero/zero and one/zero of the patients with MD, BMD and MMP, respectively. The most frequent abnormal investigations at baseline/five years later were the history (BMD/MD), the electrocardiogram (MD/MD) and the echocardiography (MMP/BMD). The mean number of abnormalities per patient with MD, BMD and MMP at baseline/five years later was 4.5/4.8, 5.6/8.3 and 4.1/3.4, respectively. CONCLUSIONS: CI is a frequent finding in patients with MD, BMD and MMP, but progression of CI within five years is found only in single cases. Patients with MD, BMD or MMP should be cardiologically investigated and treated only if CI becomes symptomatic, or if severe electrocardiographic or echocardiographic abnormalities are present.