title: Electrophysiological study with prophylactic pacing and survival in adults with myotonic dystrophy and conduction system disease.
abstract: BACKGROUND
  Up to one-third of patients with myotonic dystrophy type 1 die suddenly. Thus far, no intervention has effectively prevented sudden death.
  
  
  OBJECTIVE
  To determine whether an invasive strategy based on systematic electrophysiological studies and prophylactic permanent pacing is associated with longer survival in patients presenting with myotonic dystrophy type 1 and major infranodal conduction delays than a noninvasive strategy.
  
  
  METHODS
  A retrospective study, the DM1 Heart Registry included 914 consecutive patients older than 18 years with genetically confirmed myotonic dystrophy type 1 who were admitted to the Neurological Unit of the Myology Institute of Pitié-Salpêtrière Hospital, a teaching medical center in Paris, France, between January 2000 and December 2009.
  
  
  METHODS
  Among 486 patients whose electrocardiogram showed a PR interval greater than 200 milliseconds, a QRS duration greater than 100 milliseconds, or both, the outcome of 341 (70.2%) who underwent an invasive strategy was compared with 145 (29.8%) who underwent a noninvasive strategy. A propensity score risk adjustment and propensity-based matching analysis was used to account for selection biases.
  
  
  METHODS
  Rates of overall survival (main outcome measure) and sudden death, respiratory death, and other deaths (secondary outcome measures).
  
  
  RESULTS
  Over a median follow-up of 7.4 years (range, 0-9.9 years), 50 patients died in the invasive strategy group and 30 died in the noninvasive strategy group (hazard ratio [HR], 0.74 [95 CI, 0.47-1.16]; P = .19), corresponding to an overall 9-year survival of 74.4% (95% CI, 69.2%-79.9%). Regardless of the technique used to adjust for between-group differences in baseline characteristics, the invasive strategy was associated with a longer survival, with adjusted HRs ranging from 0.47 (95% CI, 0.26-0.84; P = .01) for a covariate-adjusted analysis of propensity-matched data to 0.61 (95% CI, 0.38-0.99; P = .047) for an analysis adjusted for propensity score quintiles. The survival difference was largely attributable to a lower incidence of sudden death, which occurred in 10 patients in the invasive strategy group and in 16 patients in the noninvasive strategy group, with HRs ranging from 0.24 (95% CI, 0.10-0.56; P = .001) for an analysis adjusted for propensity score quintiles and covariates to 0.28 (95% CI, 0.13-0.61; P = .001) for an unadjusted analysis of propensity-matched data.
  
  
  CONCLUSIONS
  Among patients with myotonic dystrophy type 1, an invasive strategy was associated with a higher rate of 9-year survival than a noninvasive strategy.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT01136330.
authors.affiliation: Pierre et Marie Curie-Paris 6 University, Myology Institute, Pitié-Salpêtrière Hospital, 75013 Paris, France. karim.wahbi@cch.aphp.fr
authors.forename: Karim
authors.initials: K
authors.lastname: Wahbi
authors.forename: Christophe
authors.initials: C
authors.lastname: Meune
authors.forename: Raphaël
authors.initials: R
authors.lastname: Porcher
authors.forename: Henri Marc
authors.initials: HM
authors.lastname: Bécane
authors.forename: Arnaud
authors.initials: A
authors.lastname: Lazarus
authors.forename: Pascal
authors.initials: P
authors.lastname: Laforêt
authors.forename: Tanya
authors.initials: T
authors.lastname: Stojkovic
authors.forename: Anthony
authors.initials: A
authors.lastname: Béhin
authors.forename: Hélène
authors.initials: H
authors.lastname: Radvanyi-Hoffmann
authors.forename: Bruno
authors.initials: B
authors.lastname: Eymard
authors.forename: Denis
authors.initials: D
authors.lastname: Duboc
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D002423:Cause of Death; D016757:Death, Sudden, Cardiac; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications / Q000401:mortality* / Q000628:therapy*; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D016019:Survival Analysis; D055815:Young Adult