Natural history of the Sprint Fidelis lead: survival analysis from a large single-center study

The purposes of our study were to: (1) determine lead failure rate in a large single-center cohort of Sprint Fidelis 6949 (Fidelis) leads, (2) define the risk of lead failure over time, (3) assess the impact of the Lead Integrity Alert (LIA) on lead failure presentation, and (4) identify independent predictors of Fidelis lead failure.

All patients who underwent implantation of a Fidelis lead between September 2004 and July 2007 were included. Demographic, clinical, and device characteristics at the time of implant and prior to failure were collected and analyzed.

A total of 971 Fidelis leads (706 men, 265 women,mean age 68.4±12.8 years) were implanted. Over a mean follow-up of 46.3 months, there were 69 lead failures(7.1%). The 5-year lead survival rate was 90.3%. The risk of lead failure demonstrated a double-peaked pattern at 34 and 61 months. In multivariate analysis, there were no independent predictors of lead failure. Inappropriate shocks(IS) were the first sign of lead failure in 29 patients (42%).The incidence (32.6% vs. 65.2%, p=0.01) and number ofIS (2.8±7.2 vs. 11.3±18.7, p=0.01) were significantly lower in patients with LIA.

This study presents a single-center experience on the natural history of the Fidelis lead. In our experience, lead survival declines at a lower rate when compared to prior reports. The risk of lead failure demonstrated a double peaked pattern at approximately 3 and 5 years. No identified variable was predictive of lead failure. LIA was effective in reducing the incidence and number of IS.