Complications associated with defibrillation threshold testing: the Canadian experience.
BACKGROUND
Defibrillation threshold (DFT) testing has traditionally been a routine part of implantable cardioverter-defibrillator (ICD) implantation, despite a lack of compelling evidence that it predicts or improves outcomes. In the past, when devices were much less reliable, DFT testing seemed prudent; however, modern ICD systems have such a high rate of successful defibrillation that many electrophysiologists now question whether DFT testing is still worthwhile, particularly since DFT testing may now be the highest acute risk component of ICD implantation.


OBJECTIVE
The purpose of this study was to systematically document complications directly attributable to intraoperative DFT testing.


METHODS
We obtained data on DFT-related complications from all 21 adult ICD implant centers in Canada, covering the period from January 1, 2000, to September 30, 2006.


RESULTS
There were a total of 19,067 ICD implants in Canada during the study period. There were three DFT testing-related deaths, five DFT testing-related strokes, and 27 episodes that required prolonged resuscitation. Two patients had significant clinical sequelae after prolonged resuscitation.


CONCLUSIONS
The risk of severe complications from intraoperative DFT testing appears small, even allowing for the underestimation of its true rate with the current study methodology. These slight but measurable risks must be considered when assessing the risk-benefit ratio of the procedure. Additional data from ongoing prospective ICD registries and/or clinical trials are required.
Birnie
David
D
University of Ottawa Heart Institute, Ottawa, Ontario, Canada. dbirnie@ottawaheart.ca <dbirnie@ottawaheart.ca>
Tung
Stanley
S
Simpson
Christopher
C
Crystal
Eugene
E
Exner
Derek
D
Ayala Paredes
Felix-Alejandro
FA
Krahn
Andrew
A
Parkash
Ratika
R
Khaykin
Yaariv
Y
Philippon
Francois
F
Guerra
Peter
P
Kimber
Shane
S
Cameron
Douglas
D
Healey
Jeffrey S
JS
D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D017147:Defibrillators, Implantable / Q000592:standards*; D004056:Differential Threshold; D022062:Electrophysiologic Techniques, Cardiac / Q000009:adverse effects*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004869:Equipment Safety; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D040242:Risk Reduction Behavior; D019564:Unnecessary Procedures