Mechanical and electrical dysfunction of Riata implantable cardioverter-defibrillator leads.

Abstract

Riata implantable cardioverter-defibrillator leads are prone to failure by conductor externalization and/or electrical dysfunction. The objectives of this study were to determine the predictors of the Riata lead failure, to assess the association of conductor externalization and electrical lead failure, and to analyse the rates of lead failure over time. Of 273 implanted Riata leads in our centre, 197 were investigated according to the Riata recall protocol, including electrical measurements by device interrogation and annually fluoroscopy. During a mean follow-up period of 5.6 ± 1.4 years, Riata lead failure was 18.8% (37 of 197) for externalization and 17.3% (34 of 197) for electrical lead failure. Electrical lead failure was correlated with time after implant. Externalization and electrical dysfunction co-existed in only 6 of 197 (3%) patients and were not related (Phi's coefficient -0.013, P = 0.85). During the second annual screening, 145 (73.6%) patients underwent fluoroscopy and 9 patients had novel externalizations resulting in an incidence of 6.72%/patient/year which was higher than expected based on cross-sectional analysis. Besides, there was a significant increase in the extent of externalization (17.65 ± 11.14 mm vs. 21.77 ± 11.95 mm, P = 0.001). In multivariate Cox regression analysis, non-ischaemic cardiomyopathy and impaired LVEF were independent predictors of externalization, and 7 Fr lead was a predictor of electrical lead failure. Riata leads show progressive and high externalization rates without correlation between externalization and electrical lead failure. Non-ischaemic cardiomyopathy and impaired LVEF are independent predictors of structural lead failure in cross-sectional analysis, whereas 7 Fr lead is a predictor of electrical lead failure.