Serial defibrillation threshold measures in man: a prospective controlled study.
Serial DFT Measures in Man.


BACKGROUND
The defibrillation threshold (DFT) may change throughout the first year following implantation of a cardioverter defibrillator, but it remains uncertain if changes are a consequence of changes in clinical condition or are related to fundamental alterations at the electrode-tissue interface. The purpose of this study was to evaluate the extent and time course of DFT changes over the first year following implantable cardioverter defibrillator (ICD) surgery when extraneous clinical and device variables potentially affecting the DFT were excluded.


RESULTS
We prospectively enrolled 61 patients undergoing epicardial or nonthoracotomy/transvenous ICD therapy into a series of follow-up studies where the DFT was measured at implant and at 1, 6, 12, and 52 weeks following implantation in a uniform manner. Stored energy DFT was measured and recorded for all patients. Patient exclusion criteria were: (1) inability to complete all five measures of the DFT; (2) institution of Class I or Class III antiarrhythmic drugs at any time during the study; (3) lead system changes (relocation or new leads) or programming changes in pulse width or current pathway; or (4) development of a significant change in their clinical status, such as decompensated congestive heart failure or acute ischemia. Only 20 of the 61 patients satisfied the criteria required to complete the study. Two of the excluded patients developed high DFTs, which required reprogramming of the current pathway. Eight patients had an epicardial lead system, and 12 had a nonthoracotomy lead system.(ABSTRACT TRUNCATED AT 250 WORDS)
Poole
J E
JE
University of Washington Medical Center, Department of Medicine, Seattle, USA.
Bardy
G H
GH
Dolack
G L
GL
Kudenchuk
P J
PJ
Anderson
J
J
Johnson
G
G
D000328:Adult; D000368:Aged; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006331:Heart Diseases / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors