Mechanisms, predictors, and trends of electrical failure of Riata leads

Abstract

Background: Riata and Riata ST implantable cardioverter-defibrillator leads have been shown to be prone to structural and electrical failure.

Objective: To determine predictors, mechanisms, and temporal patterns of Riata/ST lead electrical failure.

Methods: All 314 patients who underwent Riata/ST lead implantation at our institution with greater than or equal to 90 days of follow-up were studied. The Kaplan-Meier analysis of lead survival was performed. Results from the returned product analysis of explanted leads with electrical lead failure were recorded.

Results: During a median follow-up of 4.1 years, the Riata lead electrical failure rate was 6.6%. The rate of externalized conductors among failed leads was 57%. The engineering analysis of 10 explanted leads revealed 5 (50%) leads with electrical failure owing to breach of ethylene tetrafluoroethylene conductor coating. Female gender (hazard ratio 2.7; 95% confidence interval 1.1-6.7; P = .04) and age (hazard ratio 0.95; 95% confidence interval 0.92-0.97; P < .001) were multivariate predictors of lead failure. By using log-log analysis, we noted that the rate of Riata lead failure initially increased exponentially with a power of 2.1 but leads surviving past 4 years had a linear pattern of lead failure with a power of 1.0.

Conclusions: Younger age and female gender are independent predictors of Riata lead failure. Loss of integrity of conductor cables with ethylene tetrafluoroethylene coating is an important mode of electrical failure of the Riata lead. Further study of Riata lead failure trends is warranted to guide lead management.

Keywords: CI; ETFE; Failure rate; HR; ICD; Implantable cardioverter-defibrillator; Lead failure; confidence interval; ethylene tetrafluoroethylene; hazard ratio; implantable cardioverter-defibrillator.