Incidence, Implications, and Management of Sense-B-Noise Failure in Subcutaneous Cardioverter-Defibrillator Patients: insights from a large Multicenter Registry.

AIMS AND BACKGROUND: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) offer potentially distinct advantages over transvenous defibrillator systems. Recent randomized trials showed significantly lower lead failure rates than transvenous ICD. Still, S-ICDs remain associated with the risk of inappropriate shocks (IAS). While previous studies have reported varying causes of IAS, this study explores a rare cause of IAS, referred to as "sense-B-noise." It was recently described in cases series, but its incidence has not been studied in a large cohort of S-ICD patients.

METHODS: We retrospectively reviewed data from patients implanted with S-ICD models 1010, A209 and A219 between October 2009 and July 2023 across 9 centers in Europe and the USA. The analysis concentrated on determining the incidence and understanding the implications of sense-B-noise events. Sense-B-noise represents a rare manifestation of distinct electrogram abnormalities within the primary and alternate sensing vectors. Data were collected from medical records, device telemetry, and manufacturer reports for investigation. This registry is registered on https://clinicaltrials.gov (NCT05713708).

RESULTS: S-ICD devices of the 1,158 patients were analyzed. The median follow-up time for all patients was 46 (IQR 23-64) months. In 107 patients (9.2%) ≥ 1 IAS was observed during follow-up. Sense-B-noise failure was diagnosed in 6 (0.5% and 5.6% of all IAS) patients, in all patients the diagnosis was made after an IAS episode. Median lead dwell time in the affected patients was 23 (2-70) months. To resolve the sense-B-noise defect, in three patients reprogramming to the secondary vector was undertaken, and two patients underwent system removal with subsequent S-ICD reimplantation due to low amplitude in secondary vector. In one patient the secondary vector was initially programmed, and subsequently, a S-ICD system exchange was performed due to T-wave oversensing IAS episodes.

CONCLUSION: This multicenter analysis' findings shed light on a rare but clinically highly significant adverse event in S-ICD therapy. To our knowledge we provide the first systematic multicenter analysis investigating the incidence of sense-B-noise. Due to being difficult to diagnose and limited options for resolution, management of sense-B-noise is challenging. Complete system exchange may be the only option in some patients. Educating healthcare providers involved in S-ICD patient care is crucial for ensuring accurate diagnosis and effective management of sense-B-noise issues.