title: Predictors of short-term complications after implantable cardioverter-defibrillator replacement: results from the Ontario ICD Database.
abstract: BACKGROUND
  Complications after implantable cardioverter-defibrillator (ICD) replacement are often clinically devastating, particularly when infection or reoperation occurs. Identifying factors contributing to complications may permit identification of high-risk individuals that warrant incremental monitoring and therapy to attenuate risk. In addition, replacement may be a discretionary decision in the context of an advisory or borderline device performance and patient, device, and implanter factors that predict adverse outcome may assist in clinical decision-making.
  
  
  RESULTS
  In a prospective, multicenter, population-based registry of all ICD patients at 18 centers in Ontario, Canada, we examined 45-day complication and all-cause mortality rates from February 2007 to August 2009 in patients undergoing ICD generator replacement. Complications were determined longitudinally and were categorized as major or minor. ICD replacement was performed in 1081 of 5176 patients (20.8%) undergoing ICD implantation (age, 64.3±12.7 years; 78.5% men). In patients undergoing ICD replacement, 47 patients (4.3%) had a complication within 45 days, with 47 major complications in 28 patients (2.6%), most commonly infection (n=23), lead revision (n=35), electrical storm (n=14), and pulmonary edema (n=13). Minor complications occurred in 2.3% of patients, most commonly incisional infection (n=10) and pocket hematoma (n=10). On multivariable analysis, risk factors associated with major complications were Canadian Cardiovascular Society angina class (adjusted hazard ratio [HR], 3.70 for class 2 to 4 versus 0 to 1; P=0.027) and multiple previous procedures on the pocket (adjusted HR, 3.35 for >1 versus 1; P=0.058). Risk factors associated with any complication were the use of antiarrhythmic therapy (adjusted HR, 6.29; P=0.001), implanter volume (adjusted HR 10.4 for <60/y versus >120/y, P=0.026), and Canadian Cardiovascular Society angina class (adjusted HR, 3.00 for class 2 to 4 versus 0 to 1; P=0.031). In a Cox model with a time-dependent variable of major complication within 45 days after replacement, major complications after ICD replacement were associated with an increased risk of mortality at 45, 90, and 180 days (adjusted HR, 9.61, 12.69, and 6.41, respectively; P=0.002 to 0.039).
  
  
  CONCLUSIONS
  Risk factors associated with complications after ICD replacement include the presence of angina, antiarrhythmic therapy, increased number of previous procedures, and low implanter volume. Major complications may be associated with increased risk of subsequent mortality.
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada. akrahn@uwo.ca
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Krahn
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Lee
authors.forename: David
authors.initials: D
authors.lastname: Birnie
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Healey
authors.forename: Eugene
authors.initials: E
authors.lastname: Crystal
authors.forename: Paul
authors.initials: P
authors.lastname: Dorian
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Simpson
authors.forename: Yaariv
authors.initials: Y
authors.lastname: Khaykin
authors.forename: Douglas
authors.initials: D
authors.lastname: Cameron
authors.forename: Amir
authors.initials: A
authors.lastname: Janmohamed
authors.forename: Raymond
authors.initials: R
authors.lastname: Yee
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Chen
authors.forename: Judy
authors.initials: J
authors.lastname: Hardy
authors.forename: Jack V
authors.initials: JV
authors.lastname: Tu
mesh_terms: D000368:Aged; D002423:Cause of Death; D016009:Chi-Square Distribution; D019992:Databases as Topic; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D020878:Device Removal; D004554:Electric Countershock / Q000009:adverse effects* / Q000295:instrumentation / Q000401:mortality; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome