title: Long-term arrhythmia follow-up of patients with myotonic dystrophy.
abstract: BACKGROUND
  Myotonic dystrophy (MD) is the most common muscular dystrophy in adults and is associated with sudden death. Reported predictors of sudden death in this population include atrial tachyarrhythmias, a PR interval greater than 240 milliseconds, aberrant QRS conduction, and any degree of AV block.
  
  
  OBJECTIVE
  We sought to report on the arrhythmic outcome of a cohort of patients with a new diagnosis of genetically proven MD.
  
  
  METHODS
  We performed a retrospective review of 37 patients with genetically confirmed MD referred to our electrophysiology clinic for primary cardiac screening.
  
  
  RESULTS
  There were 25 patients with MD type 1 (MD1) and 12 patients with MD type 2 (MD2). Eight patients with MD1 (32%) had atrial fibrillation, compared to only one patient with MD2 (8.3%). Patients with MD1 were more likely to have evidence of conduction disease abnormalities (40% vs. 8.3%, P = ns) and had a higher all-cause mortality (16% vs. 0%) than those with MD2. Criteria for recommending ICD implantation were based on sudden death risk factors suggested by published literature. Eleven patients were offered an ICD, 2 refused and died within the next year. Of the 9 patients who received an ICD, 8 had MD1. Three patients received appropriate shocks, 2 for monomorphic VT, and one for polymorphic VT.
  
  
  CONCLUSIONS
  The presence of AV conduction disturbance in MD patients is associated with a greater risk for ventricular arrhythmias. MD1 was more likely to be associated with cardiac arrhythmias than MD2. The incidence of ventricular arrhythmias among those who received a primary prevention ICD was 33% over 22 months, with 2 patients experiencing monomorphic VT and one experiencing polymorphic VT.
authors.affiliation: Electrophysiology Section, Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Benhayon
authors.forename: Ricardo
authors.initials: R
authors.lastname: Lugo
authors.forename: Rutuke
authors.initials: R
authors.lastname: Patel
authors.forename: Lidia
authors.initials: L
authors.lastname: Carballeira
authors.forename: Lauren
authors.initials: L
authors.lastname: Elman
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Cooper
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D017147:Defibrillators, Implantable / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000175:diagnosis* / Q000401:mortality* / Q000628:therapy; D012189:Retrospective Studies; D013997:Time Factors
keywords: implantable cardioverter defibrillator; myopathy; myotonic dystrophy; sudden death; ventricular fibrillation; ventricular tachycardia