title: Predictors of an inadequate defibrillation safety margin at ICD implantation: insights from the National Cardiovascular Data Registry.
abstract: BACKGROUND
  Defibrillation testing is often performed to establish effective arrhythmia termination, but predictors and consequences of an inadequate defibrillation safety margin (DSM) remain largely unknown.
  
  
  OBJECTIVE
  The aims of this study were to develop a simple risk score predictive of an inadequate DSM at implantable cardioverter-defibrillator (ICD) implantation and to examine the association of an inadequate DSM with adverse events.
  
  
  METHODS
  A total of 132,477 ICD Registry implantations between 2010 and 2012 were analyzed. Using logistic regression models, factors most predictive of an inadequate DSM (defined as the lowest successful energy tested <10 J from maximal device output) were identified, and the association of an inadequate DSM with adverse events was evaluated.
  
  
  RESULTS
  Inadequate DSMs occurred in 12,397 patients (9.4%). A simple risk score composed of 8 easily identifiable variables characterized patients at high and low risk for an inadequate DSM, including (with assigned points) age <70 years (1 point); male sex (1 point); race: black (4 points), Hispanic (2 points), or other (1 point); New York Heart Association functional class III (1 point) or IV (3 points); no ischemic heart disease (2 points); renal dialysis (3 points); secondary prevention indication (1 point); and ICD type: single-chamber (2 points) or biventricular (1 point) device. An inadequate DSM was associated with greater odds of complications (odds ratio: 1.22; 95% confidence interval: 1.09 to 1.37; p = 0.0006), hospital stay >3 days (odds ratio: 1.24; 95% confidence interval: 1.19 to 1.30; p < 0.0001), and in-hospital mortality (odds ratio: 1.96; 95% confidence interval: 1.63 to 2.36; p < 0.0001).
  
  
  CONCLUSIONS
  A simple risk score identified ICD recipients at risk for an inadequate DSM. An inadequate DSM was associated with an increased risk for in-hospital adverse events.
authors.affiliation: Cardiac Electrophysiology Section, Division of Cardiology, University of California, San Diego, San Diego, California. Electronic address: jonathan.hsu@ucsd.edu.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Hsu
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, University of California, San Francisco, San Francisco, California.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marcus
authors.affiliation: Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina.
authors.forename: Sana M
authors.initials: SM
authors.lastname: Al-Khatib
authors.affiliation: Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Yongfei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Jeptha P
authors.initials: JP
authors.lastname: Curtis
authors.affiliation: Cardiac Arrhythmia Services, Southcoast Health System, Fall River, Massachusetts.
authors.forename: Nitesh
authors.initials: N
authors.lastname: Sood
authors.affiliation: Division of Cardiology, Hartford Hospital, Hartford, Connecticut.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Parker
authors.affiliation: Division of Cardiology, Hartford Hospital, Hartford, Connecticut.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kluger
authors.affiliation: Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Rachel
authors.initials: R
authors.lastname: Lampert
authors.affiliation: Cooper Medical School of Rowan University, Cooper University Hospital, Camden, New Jersey.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Russo
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000628:therapy*; D015331:Cohort Studies; D016208:Databases, Factual / Q000639:trends*; D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000639:trends*; D004554:Electric Countershock / Q000009:adverse effects / Q000639:trends*; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000639:trends*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012042:Registries; D012307:Risk Factors
keywords: adverse events; complications; defibrillation safety margin; defibrillation threshold; implantable cardioverter-defibrillator; mortality; national registries; risk score