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. 2023 May 19;25(5):euad040.
doi: 10.1093/europace/euad040.

Exploiting SMART pass filter deactivation detection to minimize inappropriate subcutaneous implantable cardioverter defibrillator therapies: a real-world single-centre experience and management guide

Christopher Monkhouse  1 , Amy Wharmby  1 , Zoe Carter  1 , Ross Hunter  1 , Mehul Dhinoja  1 , Anthony Chow  1 , Antonio Creta  1 , Shohreh Honarbakhsh  1 , Syed Ahsan  1 , Michele Orini  1   2 , Pier D Lambiase  1   2
Affiliations

Exploiting SMART pass filter deactivation detection to minimize inappropriate subcutaneous implantable cardioverter defibrillator therapies: a real-world single-centre experience and management guide

Christopher Monkhouse et al. Europace. .

Abstract

Aims: The SMART Pass™ (SP) algorithm is a high-pass filter that aims to reduce inappropriate therapy (IT) in subcutaneous internal cardiac defibrillator (S-ICD), but SP can deactivate due to low amplitude sensed R waves or asystole. The association between IT and SP deactivation and management strategies were evaluated, hypothesizing SP deactivation increases the risk of IT and device re-programming, or lead/generator re-positioning could reduce this risk.

Methods and results: Retrospective single-centre audit of Emblem™ S-ICD devices implanted 2016 to 2020 utilizing health records and remote monitoring data. Cox regression models evaluated associations between SP deactivation and IT. A total of 348 patients (27 ± 16.6 months follow-up) were studied: 73% primary prevention. Thirty-eight patients (11.8%) received 83 shocks with 27 patients (7.8%) receiving a total of 44 IT. Causes of IT were oversensing (98%) and aberrantly conducted atrial fibrillation (2%). SP deactivation occurred in 32 of 348 patients (9%) and was significantly associated with increased risk of IT (hazard ratio 5.36, 95% CI 2.37-12.13). SP deactivation was due to low amplitude R waves (94%), associated with a higher defibrillation threshold at implant and presence of arrhythmogenic right ventricular cardiomyopathy. No further IT occurred 16 ± 15.5 months after corrective interventions, with changing the sensing vector being successful in 59% of cases.

Conclusion: To reduce the risk of IT, the cause of the SP deactivation should be investigated, and appropriate reprogramming, device, or lead modifications made. Utilizing the alert for SP deactivation and electrograms could pro-actively prevent IT.

Keywords: Defibrillation; Inappropriate shocks; Oversensing; Programming; S-ICD; Subcutaneous ICD; TWOS.

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Conflict of interest statement

Conflict of interest: C.M. has received speaker fees from Abbott, Boston Scientific, Biotronik, Medtronic, and Phillips and has received consulting fees from Medtronic. As of April 2023 CM is supported by a research grant provided by Boston Scientific. Z.C. has received speaker fees from Abbott. R.H. has received speaker fees from Medtronic and Biosense Webster; educational grant from Biosense Webster; and an institutional research grant from Medtronic. A.C. has received an institutional research grant from Abbott and has received an educational grant from Abbott and Boston Scientific. P.D.L. has received research grants and speaker fees from Boston Scientific, Abbott, and Medtronic and is supported by UCL/UCLH Biomedicine NIHR and Barts BRC.

Figures

Figure 1
Figure 1
Kaplan–Meier survival curve for inappropriate therapy with SMART Pass™ ON and SMART Pass™ OFF. Timelines start from date of implant.
Figure 2
Figure 2
SMART Pass™ deactivation recordings. * Highlights point at which SP deactivates.
Figure 3
Figure 3
Proposed management guide for SMART Pass™ disablement.
See this image and copyright information in PMC

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