title: Cardiac involvement in myotonic dystrophy: a nationwide cohort study.
abstract: OBJECTIVE
  To quantify the association between myotonic dystrophy (DM) and cardiac disease in a nationwide cohort.
  
  
  RESULTS
  We identified a nationwide cohort of 1146 DM patients (period 1977-2011) using the National Patient Registry (NPR) and a subcohort of 485 patients who had undergone genetic testing for DM1. Information on incident cardiac diseases was obtained from the NPR. We estimated standardized incidence ratios (SIRs) of cardiac disease compared with the background population, overall and according to selected diagnostic subgroups (cardiomyopathy, heart failure, conduction disorders, arrhythmias, and device implantation). In the DM cohort, SIR for any cardiac disease was 3.42 [95% confidence interval (CI) 3.01-3.86]; for a cardiac disease belonging to the selected subgroups 6.91 (95% CI: 5.93-8.01) and for other cardiac disease 2.59 (95% CI: 2.03-3.25). For a cardiac disease belonging to the selected subgroups, the risk was particularly high in the first year after DM diagnosis [SIR 15.4 (95% CI: 10.9-21.3)] but remained significantly elevated in subsequent years [SIR 6.07 (95% CI: 5.11-7.16]). The risk was higher in young cohort members [e.g. 20-39 years: SIR 18.1 (95% CI: 12.3-25.8)] compared with older [e.g. 60-79 years: SIR 3.99 (95% CI: 2.98-5.23)] but remained significantly increased in all age categories. Results were similar in separate analyses of the genetically confirmed DM1 patients.
  
  
  CONCLUSIONS
  Myotonic dystrophy is strongly associated with cardiac disease. The risk is pronounced in the young and remains elevated throughout life, stressing the importance of lifelong cardiac follow-up from time of DM diagnosis.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, Copenhagen S, Denmark mxd@ssi.dk.
authors.forename: Marie
authors.initials: M
authors.lastname: Lund
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, Copenhagen S, Denmark.
authors.forename: Lars Jorge
authors.initials: LJ
authors.lastname: Diaz
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, Copenhagen S, Denmark.
authors.forename: Mattis Flyvholm
authors.initials: MF
authors.lastname: Ranthe
authors.affiliation: Unit for Inherited Cardiac Diseases, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Petri
authors.affiliation: Department of Clinical Genetics, Molecular Genetic Laboratory, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Duno
authors.affiliation: Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Inger
authors.initials: I
authors.lastname: Juncker
authors.affiliation: Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Hans
authors.initials: H
authors.lastname: Eiberg
authors.affiliation: Neuromuscular Research Unit, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Vissing
authors.affiliation: Unit for Inherited Cardiac Diseases, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Bundgaard
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, Copenhagen S, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, Copenhagen S, Denmark Department of Medicine, Stanford School of Medicine, Stanford, CA, USA.
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006331:Heart Diseases / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications* / Q000453:epidemiology; D012307:Risk Factors; D055815:Young Adult
keywords: Cardiac disease; Epidemiology; Myotonic dystrophy