Discrepancies between the upper limit of vulnerability and defibrillation threshold: prevalence and clinical predictors.
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.
Gurevitz
Osnat T
OT
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Friedman
Paul A
PA
Glikson
Michael
M
Trusty
Jane M
JM
Ballman
Karla V
KV
Rosales
Ana G
AG
Hayes
David L
DL
Hammill
Stephen C
SC
Swerdlow
Charles D
CD
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*