title: Discrepancies between the upper limit of vulnerability and defibrillation threshold: prevalence and clinical predictors.
abstract: BACKGROUND
  Upper limit of vulnerability (ULV) has a strong correlation with defibrillation threshold (DFT) in patients with implantable cardioverter defibrillators (ICDs). Significant discrepancies between ULV and DFT are infrequent. The aim of this study was to characterize patients with such discrepancies.
  
  
  RESULTS
  The ULV and DFT were determined in 167 ICD patients. Univariate and multivariate analyses were used to evaluate clinical predictors of a significant difference (> or =10 J) between ULV and DFT. Only 8 patients (5%) had > or =10 J difference. ULV exceeded DFT in all of them. Absence of coronary artery disease (6/8 vs 48/159 patients; P = 0.05) and absence of documented ventricular arrhythmias (4/8 vs 12/159 patients; P = 0.01) were the only independent predictors of a significant ULV-DFT discrepancy.
  
  
  CONCLUSIONS
  Significant discrepancies between ULV and DFT occur in 5% of patients with ICDs. Absence of coronary disease and documented ventricular arrhythmias predict such a discrepancy. At ICD implant, DFT testing is recommended in these patients and in patients with a high (>20 J) ULV before first-shock energy and the need for lead repositioning are determined.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Osnat T
authors.initials: OT
authors.lastname: Gurevitz
authors.forename: Paul A
authors.initials: PA
authors.lastname: Friedman
authors.forename: Michael
authors.initials: M
authors.lastname: Glikson
authors.forename: Jane M
authors.initials: JM
authors.lastname: Trusty
authors.forename: Karla V
authors.initials: KV
authors.lastname: Ballman
authors.forename: Ana G
authors.initials: AG
authors.lastname: Rosales
authors.forename: David L
authors.initials: DL
authors.lastname: Hayes
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Hammill
authors.forename: Charles D
authors.initials: CD
authors.lastname: Swerdlow
mesh_terms: D000368:Aged; D017147:Defibrillators, Implantable / Q000009:adverse effects* / Q000592:standards; D004554:Electric Countershock / Q000379:methods* / Q000592:standards; D019544:Equipment Failure Analysis / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D009518:New York; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013610:Tachycardia / Q000628:therapy*; D014693:Ventricular Fibrillation / Q000209:etiology* / Q000517:prevention & control / Q000628:therapy*