Introduction: We evaluated the frequency of appropriate and inappropriate shocks and survival in patients using dual-zone programming versus single-zone programming.
Methods and results: For the ALTITUDE REDUCES study, patients were followed for 1.6 ± 1.1 years. The 12-month incidence of any shock was lower for dual-versus single-zone programmed detection at rates ≤170 bpm and between 170-200 bpm (P < 0.001). Appropriate shock rates at 1 year were also lower with dual-zone programming in these rate intervals (single zone 9.1%, 5.4%, P < 0.001, dual zone 6.7%, 4.7%, P < 0.02). There were no detectable differences between single- and dual-zone shock incidence at detection rates ≥ 200 bpm (P = 0.14). Inappropriate shock incidence was less with dual- versus single-zone detection at all detect rates <200 bpm, but not at rates ≥200 bpm (P < 0.001, P = 0.37). The lowest risk of appropriate and inappropriate shock was associated with dual-zone programming and detection rates ≥200 bpm (2.1%). Dual-zone detection was associated with more nonsustained and diverted therapy episodes but these patients did not have an increased risk of death compared to patients with single-zone programming. Patients programmed to low detection rate, single-zone detection and shock-only therapy also had the highest preshock mortality risk (P = 0.05).
Conclusions: Shock incidence is lowest with either single- or dual-zone detection ≥200 bpm. For detection rates <200 bpm, dual-zone programming is associated with a reduction in the incidence of total shocks, appropriate shocks, and inappropriate shocks.
© 2011 Wiley Periodicals, Inc.