Progressive decrease in amplitude of intracardiac ventricular electrogram and higher left ventricular ejection fraction are associated with conductors' externalization in Riata leads

Increased rates of structural abnormalities including externalized conductors have been reported in the Riata family of implantable cardioverter-defibrillator leads (St Jude Medical). Little is known about their reliability and the time lag for emergence of functional or structural abnormalities.

Thirty-six patients who received small-caliber leads of the Riata family and who completed face-profile flouroscopies, repeated at every 6 months were included. We assessed the prevalence of conductors' externalization and its relation to abnormal electrical parameters or adverse events. Thirty-six patients, mean age = 64 ± 10 years, with at least 7-month completed fluoroscopy follow-up were included in the analysis. Externalized conductors were identified in 12 (33%) patients after a 53-month (13–114) mean delay. A higher left ventricular ejection fraction (LVEF): 47 ± 13 vs. 33 ± 12%, P = 0.04, and a progressive decrease (≥30% of the initial value) in amplitude of ventricular electrogram 9/12 (75%) vs. 4/24 (17%), P = 0.03 were independently associated with the fluoroscopic failures. Detection of the conductors' externalization was preceded by an electrical lead abnormality in 10 (83%) patients.

Repeated face-profile fluoroscopies allowed detection of conductors' externalization in 33% of patients implanted with Riata leads. Better LVEF and a progressive decrease in amplitude of intracardiac ventricular electrogram were independently associated with externalized conductors. The structural abnormality was preceded by an electrical lead dysfunction 83% of patients.