Failure of Elective Replacement Indicator to Predict End‐of‐Life of the Automatic Implantable Cardioverter‐Defibrillator

Abstract

A major limitation in the use of the automatic implantable cardioverter-defibrillator (AICD) is limited battery longevity and the absence of an accurate and precise end-of-life indicator. An elective replacement indicator, or ERI, was proposed by the manufacturer of the AICD in 1985. This ERI was evaluated in nine patients with AICDs. The ERI was exceeded at a mean of 10.9 +/- 3.0 months after implantation. Although 0.6 +/- 0.4 months of battery life were predicted to remain before battery failure, the devices were followed for 6.0 +/- 3.8 months (p = 0.002) during which time no device failed. Although 28.9 +/- 21.9 seconds of charging time were predicted to remain, 103.5 +/- 67.9 seconds were shown to be available by magnet charge time testing (p = 0.01). Thus, the ERI of the AICD, as originally proposed by its manufacturer, consistently underestimated both the predicted time to end-of-life as well as the cumulative charging time remaining before end-of-life for each AICD examined. We propose that this ERI not be used to predict end-of-life of the AICD. A "new" ERI has been recommended.