A Prospective Randomised CompArative trial of SubcutanEous ImplanTable CardiOverter-DefibrillatoR ImplANtation with and without DeFibrillation Testing

Implantable Cardioverter Defibrillator (ICD) implant improves survival in
patients with a higher risk for sudden cardiac death. There are 2 types of ICD
available; transvenous ICD (TV-ICD) and subcutaneous ICD (S-ICD). During ICD
implant, defibrillation testing (DFT) is performed to test functionality of the
device. However, DFT can be associated with complications such as inability to
convert, complications arising from general anaesthesia, prolonged
resuscitation, stroke and death. Whereas DFT may be associated with
complications, the benefit of DFT is debated as literature shows there is only
a modest average effect of DFT, if any, on mortality, shock efficacy or safety.
Recently it was shown in a randomized controlled trial called 'SIMPLE' that
routine defibrillation testing of TV-ICDs at the time of implant does not
improve shock efficacy or reduce arrhythmic death. For S-ICD there is only
limited data available of the effect of DFT on S-ICD efficacy. Data have
however shown that the conversion efficacy of the S-ICD is comparable to
TV-ICD.

DFT is currently performed in standard S-ICD implants, but is omitted in
specific cases. However, an alternative method to evaluate the correct position
may be desired when omitting DFT. The PRAETORIAN Score is developed using
computer modelling data on factors influencing defibrillation thresholds. The
PRAETORIAN score represents the chance of a patient having an elevated
defibrillation threshold and consequently failing a DFT or conversion of a
spontaneous arrhythmia episode. THe score was retrospectiely validated in two
studies with 180 and 321 patients.

It was reported that most S-ICD implants are performed under general
anesthesia, however other anesthesia protocols are used as well. One of the
most predominant factors to use general anesthesia is the performance of the
DFT. If this is omitted, other anesthesia protocols may be a good option for
many patients as well.

The primary objective is to test the hypothesis that S-ICD implant without DFT
with PRAETORIAN Score is non-inferior to S-ICD implant with DFT with regard to
first shock efficacy in spontaneous events. The secondary objective is to
evaluate the PRAETORIAN score and to evaluate anaesthesia protocols for
implantation.

A single-blinded, prospective, multicenter, international, two-arm randomised
comparative trial.

Patients will be randomised between S-ICD implant with or without
defibrillation test.

This study is designed to minimally interfere with standard of care procedure
in participating hospitals. There will be no extra study visits, patients will
visit the outpatient clinic according to the regular S-ICD follow-up routine as
determined by the participating hospital. The risk associated with this study
is minimal as DFT is recommended but not mandatory in these patients and
already being omitted in certain patients. Furthermore, previous studies have
shown that DFT in TV-ICD patients does not reduce the risk of arrhythmic death
but does expose patients to the risk of complications of DFT. S-ICD studies
have shown similar shock efficacy compared to TV-ICD studies, therefore similar
effect of omitting of DFT in SICD is expected.