title: Association of Antitachycardia Pacing or Shocks With Survival in 69,000 Patients With an Implantable Defibrillator.
abstract: OBJECTIVE
  Antitachycardia pacing (ATP) is an effective treatment for ventricular tachycardia (VT) and can reduce the frequency of shocks in patients with an implantable cardioverter defibrillator (ICD). The association between survival and ATP, as compared to a shock, has not been confirmed in a large patient population. This study aims to determine if patients with an ICD receiving ATP have lower mortality, as compared to those receiving shock.
  
  
  METHODS
  Sixty-nine thousand three hundred and sixty-eight patients underwent ICD implantation between October 2008 and May 2013 and were enrolled in the remote monitoring network Merlin.net™ (St. Jude Medical, St. Paul, MN, USA). Patients were categorized into three groups based on the type of ICD therapy received during follow-up: no therapy (N = 47,927), ATP (N = 8,049), and shock (N = 13,392) groups. Survival was determined by linking implant records to the Social Security Death Index.
  
  
  RESULTS
  The no therapy (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.56-0.64, P < 0.001) and ATP (HR 0.70, 95% CI 0.64-0.77, P < 0.001) groups were associated with a lower mortality risk than the shock group. These results were unaffected by age, gender, device type, atrial fibrillation (AF) burden, or ventricular rate. ATP was effective in 85% of episodes and ATP effectiveness was dependent on the ventricular rate.
  
  
  CONCLUSIONS
  Mortality rates were higher in ICD patients who received only ATP compared to no therapy, but ICD patients who received a shock had higher mortality compared to both groups. Furthermore, the data suggest that age, gender, device type, AF burden, and rate of arrhythmia do not change the trend of higher mortality in patients receiving ICD shock compared to ATP alone.
authors.affiliation: INOVA Fairfax Hospital, Fairfax, Virginia, USA.
authors.forename: S Adam
authors.initials: SA
authors.lastname: Strickberger
authors.affiliation: Texas Cardiac Arrhythmia Institute, Austin, Texas, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Canby
authors.affiliation: Temple University Health System, Philadelphia, Pennsylvania, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Cooper
authors.affiliation: Stern Cardiovascular Foundation, Memphis, Tennessee, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Coppess
authors.affiliation: University of Southern California, Los Angeles, California, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Doshi
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Roy
authors.initials: R
authors.lastname: John
authors.affiliation: St. Jude Medical, Sylmar, California, USA.
authors.forename: Allison T
authors.initials: AT
authors.lastname: Connolly
authors.affiliation: St. Jude Medical, Sylmar, California, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Roberts
authors.affiliation: St. Jude Medical, Sylmar, California, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Karst
authors.affiliation: Ohio State University, Columbus, Ohio, USA.
authors.forename: Emile G
authors.initials: EG
authors.lastname: Daoud
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D005260:Female; D006339:Heart Rate; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: antitachycardia pacing; implantable cardioverter defibrillator; remote monitoring