Prospective blinded evaluation of a novel sensing methodology designed to reduce inappropriate shocks by the subcutaneous implantable cardioverter-defibrillator.

BACKGROUND

Most inappropriate shocks from the subcutaneous implantable cardioverter-defibrillator (S-ICD) are caused by cardiac oversensing. A novel sensing methodology, SMART Pass (SP; Boston Scientific Corporation, Natick, MA), aims to reduce cardiac oversensing.

OBJECTIVE

The purpose of this study was to evaluate the effect of SP on shocks in ambulatory patients with S-ICD.

METHODS

Patients implanted in 2015-2016 and enrolled in a remote patient monitoring system were included and followed for 1 year. Shocks were adjudicated by 3 independent blinded reviewers as appropriate or inappropriate. Shock incidence was calculated for patients with SP programmed enabled or disabled at implantation, censoring patients when SP programming changed or at the last transmission. The SP setting (enabled vs disabled) was modeled as a time-dependent Cox regression variable.

RESULTS

The cohort consisted of 1984 patients, and a total of 880 shocks were adjudicated. At implantation, SP was enabled in 655 patients (33%) and disabled in 1329 patients (67%). SP reduced the risk for the first inappropriate shock by 50% (P < .001) and the risk for all inappropriate shocks by 68% (P < .001) in multivariate analysis adjusted for age and device programming. The incidence of inappropriate shocks was 4.3% in the SP enabled arm vs 9.7% in the SP disabled arm. The incidence of appropriate shocks was similar (5.2% vs 6.6%; P = .18) along with the time to treat the first appropriate shock (17.4 seconds vs 16.7 seconds; P = .92) for SP enabled vs disabled, respectively.

CONCLUSION

This prospective blinded evaluation of the SP filter demonstrates that enabling the SP filter results in a significant reduction of inappropriate shocks by the S-ICD without a negative effect on appropriate shocks.