title: Clinical course and long-term follow-up of patients receiving implantable cardioverter-defibrillators.
abstract: BACKGROUND
  Implantable cardioverter-defibrillators (ICDs) are increasingly used for primary and secondary prevention of sudden cardiac death. Defibrillators were introduced into clinical practice in 1980. Since that time, factors affecting long-term survival and the natural history of defibrillator patients have not been described.
  
  
  OBJECTIVE
  The purpose of this study was to identify clinical predictors of long-term survival in patients receiving ICDs.
  
  
  METHODS
  The prognostic value of several clinical variables on the likelihood of survival or appropriate ICD therapy in 1,382 consecutive patients receiving ICDs from 1980 to 2003 were evaluated. Data were collected at the time of device implantation, and follow-up was completed through March 2005.
  
  
  RESULTS
  In 70 +/- 51 months of follow-up (range 0-282 months), 792 patients died and 421 patients received appropriate ICD therapy at least once. Age, left ventricular ejection fraction, New York Heart Association (NYHA) functional class, Charlson comorbidity index, and antiarrhythmic drug use correlated with mortality. beta-Blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. Only NYHA functional class correlated with ICD therapy. Patients free of shocks for the first 5 years after ICD implantation had continued risk of arrhythmia recurrence.
  
  
  CONCLUSIONS
  The heart failure characteristics of patients predicted ICD shock probability and survival better than the arrhythmia characteristics or the underlying heart disease. Antiarrhythmic drug use was associated with increased mortality. Beta-blocker and angiotensin-converting enzyme inhibitor use was associated with improved survival. A measurable arrhythmic risk even after prolonged shock-free intervals indicates the need for continued ICD therapy in all patients with appropriate ICD indications.
authors.affiliation: Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Harikrishna
authors.initials: H
authors.lastname: Tandri
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Griffith
authors.forename: Tania
authors.initials: T
authors.lastname: Tang
authors.forename: Khurram
authors.initials: K
authors.lastname: Nasir
authors.forename: Omeed
authors.initials: O
authors.lastname: Zardkoohi
authors.forename: Chandrasekhar Vasam
authors.initials: CV
authors.lastname: Reddy
authors.forename: Melissa
authors.initials: M
authors.lastname: Capps
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Donahue
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000150:complications / Q000401:mortality / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome