Abstract
Background
The entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) eliminates
the need for transvenous leads, and therefore has the potential to improve lead-longevity
and reduce lead-related complications. The S-ICD has a morphology-based sensing algorithm
of which inappropriate shocks have been reported.
Methods
We analyzed the incidence, predictors and management of inappropriate shocks in the
EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up
data from clinical centers in Europe and New Zealand.
Results
During a follow-up of 21 ± 13 months, 48 out of 581 S-ICD patients (71% male, age 49 ± 18 years) experienced 101 inappropriate shocks (8.3%). The most common cause was cardiac
signal oversensing (73%), such as T-wave oversensing. Eighteen shocks (18%) were due
to supraventricular tachycardias (SVT), of which 15 occurred in the shock-only zone.
Cox-proportional hazard modeling using time-dependent covariates demonstrated that
patients with a history of atrial fibrillation (HR 2.4) and patients with hypertrophic
cardiomyopathy (HR 4.6) had an increased risk for inappropriate shocks, while programming
the primary vector for sensing (from xyphoid to V6) reduced the risk. Reprogramming
or optimization of SVT treatment after the first clinical event of inappropriate shock
was successful in preventing further inappropriate shocks for cardiac oversensing
and SVT events.
Conclusions
Inappropriate shocks, mainly due to cardiac oversensing, occurred in 8.3% of the S-ICD
patients. Patients with hypertrophic cardiomyopathy or a history of atrial fibrillation
were at increased risk, warranting specific attention for sensing and programming
in this population.
Keywords
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Article info
Publication history
Published online: May 22, 2015
Accepted:
May 17,
2015
Received:
May 11,
2015
Identification
Copyright
© 2015 Published by Elsevier Inc.
