Abstract 11384: Performance of ICD Lead Integrity Alert for Diagnosis of Riata Lead Failures
Introduction: The Lead Integrity Alert (LIA) was developed for Medtronic ICDs to reduce inappropriate shocks for rapid, oversensing (OS) caused by Fidelis® conductor fractures. Its performance has not been reported for leads prone to insulation lead failure (LF), such as St. Jude’s Riata®.
Methods: We analyzed data from all 1,944 LIA-enabled Medtronic ICDs in the CareLink® remote monitoring network connected to Riata® leads. LIA monitors 3 criteria: 2 for transient, rapid OS and 1 for relative change in pace-sense impedance (Z): >75% above or < 50% below baseline. It triggers an alert if any 2 criteria are met. Each alert was adjudicated based on ICD stored EGMs/diagnostics and clinical data as a true-positive lead event or false-positive event. EGMs were reviewed for characteristics of LFs.
Results: During 2,098 patient (pt)-years of LIA follow-up (median 0.9 years/pt), there were 30 alerts, 21 lead events (70%) and 9 false positives (30%). Lead events included 20 LFs and 1 dislodgment. LIA was triggered only by OS in 17 LFs (85%), only by Z in 2 (10%), and by both in 1 (5%). Overall, OS alone identified more than 5 additional LFs for every LF identified by Z (P<0.001). Prior to LIA trigger, the 17 LFs that satisfied only OS had stable Z (minimum 394±122 Ω, maximum 449±125 Ω, range 55 ± 26 Ω). Inappropriate shocks occurred in 2 pts (10%). In 11 pts (55%) with LF, OS was caused by distinctive isolated ‘Spikes” (transient deflections lasting only 1 digital sampling interval) with negative polarity (Figure). The 9 false-positive alerts were caused by T-wave oversensing (4), electromagnetic interference (3), and ventricular fibrillation (2). The overall false-positive alert rate was 1 every 233 pt-years.
Conclusions: Riata LFs identified by LIA are detected primarily by transient OS, often of distinctive spikey signals. Z is usually stable. The rate of inappropriate shocks is low for LIA-enabled ICDs. Rare false-positive LIA alerts identify clinically-significant events.
- © 2012 by American Heart Association, Inc.