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

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.

Intra-Abdominal Hemorrhage Triggering Inappropriate Therapy From a Subcutaneous Defibrillator

“…Any process that diminishes R-wave amplitude risks automatic SP deactivation, including air in the device pocket or progression of a myopathic process such as arrhythmogenic right ventricular cardiomyopathy. 8 Other triggers include changes in QRS vectors caused by cardiac remodeling 9 or QRS configuration as a result of electrolyte abnormalities, 10 periodic changes in axis with arrhythmias such as aberrant SVT or nonsustained ventricular tachycardia, and sustained pauses. 8 …”

“… 8 Other triggers include changes in QRS vectors caused by cardiac remodeling 9 or QRS configuration as a result of electrolyte abnormalities, 10 periodic changes in axis with arrhythmias such as aberrant SVT or nonsustained ventricular tachycardia, and sustained pauses. 8 …”

“…Our case of SP deactivation from intra-abdominal hemorrhage was not immediately reversible, and in such cases, defibrillation was temporarily disabled until the trigger was addressed. 8 Once a trigger is addressed, a device interrogation to establish new sensing templates and reactivate SP should be conducted.…”

Impact of ventricular tachycardia ablation in subcutaneous implantable cardioverter defibrillator carriers: a multicentre, international analysis from the iSUSI project

“…The PRAETORIAN score was collected as per existing definition, either from a two-projection post-procedural chest X-ray or intra-procedurally. 17–19 Baseline device programming setup and the rate of SMART Pass algorithm use for inappropriate shock risk reduction 20 were collected as well. Follow-up strategy was left to each centre’s policy, with most patients being evaluated at 1, 6, and 12 months and every 6 months thereafter.…”

Comparison of automated subcutaneous defibrillator screening between different pacing sites in cardiac pacing device carriers

“…Moreover, SMART Pass™ algorithm activation should be mandatory in order to avoid inappropriate therapy. 2 …”