How Much Scrutiny and Stress Can the Fidelis Lead Withstand?

The implantable cardioverter-defibrillator lead has undergone numerous design and manufacturing changes over the last 25 years aimed at improving patient care and outcomes. It is widely accepted that implantable cardioverter-defibrillator leads, similar to pacemaker leads, have a finite life. The design of an implantable cardioverter-defibrillator lead is more complex than that of a pacemaker lead, and the propensity for failure is greater. Estimates of the rate of failure vary, but during follow-up at 10 years, the failure rate may be as high as 20%.1 Factors that affect implantable cardioverter-defibrillator lead performance include the implanting physician, the patient, and specific characteristics related to lead design. Most lead failures are multifactorial.Article see p 358In October 2007, Medtronic voluntarily discontinued sales of the Sprint Fidelis family of leads because of a trend toward decreased survival of the lead compared with an earlier model, the Sprint Quattro. At the time of discontinuation, the lead had been implanted in 268 000 patients worldwide; by October 2010, an estimated 166 000 Fidelis leads remained active worldwide. Fidelis lead failure can be traced to fracture of the pace/sense electrodes, the shocking coils, or both. Failure is usually the result of fracture of either the cable to the anode (ring electrode) near the lead tip or the coil to the cathode (tip electrode) near the anchoring sleeve. The most common complication of lead fracture is rapid oversensing of electrical noise and delivery of inappropriate shocks, but failure to deliver bradycardia pacing and anti tachycardia pacing due to elevated impedance or inhibition of pacing by oversensing has also been reported.2 …