title: Arrhythmic Risk Following Recovery of Left Ventricular Ejection Fraction in Patients with Primary Prevention ICD.
abstract: BACKGROUND
  Left ventricular ejection fraction (LVEF) recovers during follow-up in a significant proportion of patients implanted with a cardioverter defibrillator (ICD) for primary prevention. Little is known about the midterm arrhythmic risk in this population, particularly in relation to the presence or absence of ischemic cardiomyopathy.
  
  
  RESULTS
  We retrospectively analyzed 286 patients with an ICD implanted for primary prevention between 2002 and 2010. Patients were divided into two groups based on their last LVEF assessment: (1) Recovery, defined as an LVEF > 35%; and (2) No-Recovery, defined as an LVEF ≤ 35%. Kaplan-Meir curves and multivariate Cox regression analysis were performed separately for patients with ischemic (211 patients) and nonischemic (75 patients) cardiomyopathy. Forty-nine patients (17.1%) had LVEF recovery to >35% at last follow-up. Overall, 72 patients (25.2%) experienced ventricular arrhythmias requiring ICD therapy during a median follow-up of 4.4 years. With multivariate Cox regression, LVEF recovery was associated with a lower arrhythmic risk in the whole cohort (hazard ratio [HR]: 0.38 [0.13-0.85]; P = 0.02) and in the nonischemic cardiomyopathy cohort (HR: 0.10 [0.005-0.55]; P = 0.005), but not in the ischemic cardiomyopathy cohort (HR: 0.84 [0.25-2.10]; P = 0.74).
  
  
  CONCLUSIONS
  In conclusion, patients with nonischemic cardiomyopathy who improved their LVEF to >35% after primary prevention ICD implantation were at very low absolute arrhythmic risk. Our study raises the possibility that the LVEF cutoff to safely withhold ICD replacement might be higher in patients with ischemic compared to nonischemic cardiomyopathy. This will need to be confirmed in prospective studies.
authors.affiliation: Faculty of Medicine, CHU de Québec, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Berthelot-Richer
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Francis
authors.initials: F
authors.lastname: Bonenfant
authors.affiliation: Faculty of Medicine, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Clavel
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Farand
authors.affiliation: Faculty of Medicine, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Philippon
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Felix
authors.initials: F
authors.lastname: Ayala-Paredes
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Btissama
authors.initials: B
authors.lastname: Essadiqi
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Mariano Gonzalo
authors.initials: MG
authors.lastname: Badra-Verdu
authors.affiliation: Department of Medicine, Cardiovascular Division, Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Roux
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging / Q000401:mortality* / Q000517:prevention & control*; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000401:mortality* / Q000517:prevention & control*; D015897:Comorbidity; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011322:Primary Prevention; D011792:Quebec / Q000453:epidemiology; D020127:Recovery of Function; D012189:Retrospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D015996:Survival Rate; D016896:Treatment Outcome
keywords: arrhythmic risk; implantable cardioverter defibrillator; left ventricular ejection fraction recovery; nonischemic cardiomyopathy