The SMART Pass 2.0 algorithm reduced the rate of inappropriate therapies to 0.0297 per patient-year, compared to 0.0514 with SP V1 and 0.1471 without SP, primarily by minimizing T-wave oversensing.
Cohort (n=661)
No
Does the SMART Pass 2.0 algorithm reduce the burden of inappropriate therapies in patients with subcutaneous implantable cardioverter defibrillators?
The SMART Pass 2.0 algorithm update in subcutaneous ICDs significantly reduces inappropriate therapies, particularly those driven by T-wave oversensing.
Absolute Event Rate: 0.0297% vs 0.1471%
Abstract Background/Introduction The SMART Pass (SP) algorithm is a high-pass filter designed to reduce inappropriate therapies (IT) in subcutaneous implantable defibrillators (SICDs), predominantly by minimizing T-wave oversensing (TWOS). However, SP can automatically deactivate itself, significantly increasing the risk of IT. In July 2022, the "SP 2.0" update was introduced to further mitigate IT risk by raising the threshold for SP deactivation and implementing a new alert system. This update notifies physicians of recorded episodes via a yellow alert transmission through the LATITUDE remote monitoring system. Purpose This study aimed to determine whether the updated "SP 2.0" reduces the burden of inappropriate therapies, particularly TWOS-related IT. Methods This was a retrospective study conducted at a tertiary cardiac centre, analysing all episodes recorded in SICD patients via the LATITUDE remote monitoring system. Therapy episodes were classified as inappropriate if they occurred in the absence of ventricular tachycardia (VT) or ventricular fibrillation (VF). Each treated event was defined as a single discrete episode, regardless of the number of individual shocks delivered. Device software versions were identified through LATITUDE transmission logs, enabling calculation of follow-up duration for each version. Patients were categorized into three groups based on software version: No SP, SP V1, and SP V2. The primary endpoint was the rate of IT per patient-year, with a sub-analysis categorizing the causes of IT. Results A total of 661 SICD patients (mean age: 43.4 ± 14.5 years) were observed, with 467 recorded episodes, of which 269 were treated events. The overall burden of IT and TWOS-driven IT declined with each SP iteration. The first IT rate per patient-year was 0.1471 in patients without SP, 0.0514 in SP V1, and 0.0297 in SP V2. The cumulative IT burden also decreased with each software version. TWOS-related IT was 0.147 per year in the No SP group, 0.026 per year in SP V1, and 0.006 per year in SP V2. Other causes of IT, including myopotentials and Sense Node B, remained consistent across software versions. Air-related inappropriate therapy peaked with SP V1 but declined following changes in implant techniques. Conclusion SP 2.0 reduces the burden of IT, particularly TWOS-related IT, further aligning SICD IT rates with modern transvenous ICDs. The introduction of SP deactivation alerts enables earlier detection and intervention, likely contributing to the observed reduction in IT by facilitating SP reactivation, sensing vector adjustments, and optimization of device and lead placement. These improvements complement algorithmic refinements that reduce the likelihood of automatic SP deactivation. Future advancements could explore multi-vector sensing or modular device communication to further minimise IT rates further.Figure 1 Figure 2
Monkhouse et al. (Sat,) conducted a cohort in Subcutaneous implantable cardioverter defibrillator (SICD) patients (n=661). SMART Pass 2.0 algorithm vs. No SMART Pass and SMART Pass V1 was evaluated on Rate of inappropriate therapies (IT) per patient-year. The SMART Pass 2.0 algorithm reduced the rate of inappropriate therapies to 0.0297 per patient-year, compared to 0.0514 with SP V1 and 0.1471 without SP, primarily by minimizing T-wave oversensing.