title: Cardiac manifestations of myotonic dystrophy type 1.
abstract: OBJECTIVE
  To estimate the degree of cardiac involvement regarding left ventricular ejection fraction, conduction abnormalities, arrhythmia, risk of sudden cardiac death (SCD) and the associations between cardiac involvement and cytosine-thymine-guanine (CTG)-repeat, neuromuscular involvement, age and gender in patients with myotonic dystrophy type 1 (MD1).
  
  
  RESULTS
  A Pub-Med search for the period 1980 to 2010 was performed according to specified criteria. Cardiac parameters including left ventricular ejection fraction (LVEF), conduction abnormalities and arrhythmia were compiled and only studies without ascertainment bias were included. Eighteen studies, 1828 MD1-patients, were included. The prevalence of atrioventricular block grade 1 (AVB1) was 28.2%, QTc>440 ms 22%, QRS>120 ms 19.9%, frequent ventricular premature contractions (VPC) 14.6%, atrial fibrillation/flutter (AF/AFL) 5%, right/left bundle branch block (RBBB/LBBB) 4.4/5.7% and non-sustained ventricular tachycardia (NSVT) 4.1%. Left ventricular systolic dysfunction (LVSD) was reported in 7.2% of the patients. There was an overall positive association between CTG-repeat size and cardiac involvement and between the degree of neuromuscular and cardiac involvement. Male gender and age were positively associated with arrhythmia and conduction abnormalities. The prevalence of pacemaker- (PM) and implantable cardioverter defibrillator-(ICD) implantations were 4.1% and 1.1%, respectively. The risk of SCD in this MD1-population was 0.56% per year.
  
  
  CONCLUSIONS
  MD1-patients have a high level of cardiac morbidity and mortality, strongly emphasizing the need of pre-symptomatic screening for arrhythmia and heart failure, as effective and well-documented preventive means are available.
authors.affiliation: Department of Cardiology, National University Hospital Rigshospitalet, Copenhagen, Denmark. Hellepetri1@gmail.com
authors.forename: Helle
authors.initials: H
authors.lastname: Petri
authors.forename: John
authors.initials: J
authors.lastname: Vissing
authors.forename: Nanna
authors.initials: N
authors.lastname: Witting
authors.forename: Henning
authors.initials: H
authors.lastname: Bundgaard
authors.forename: Lars
authors.initials: L
authors.lastname: Køber
mesh_terms: D006331:Heart Diseases / Q000209:etiology*; D006801:Humans; D009223:Myotonic Dystrophy / Q000150:complications*