A Better Method for Preventing Adverse Clinical Events Caused by Implantable Cardioverter-Defibrillator Lead Fractures?

Abstract

In October 2007, the Medtronic Sprint Fidelis implantable cardioverter-defibrillator (ICD) lead was voluntarily withdrawn from the market by the manufacturer because of a higher-than-expected fracture rate.1 Most Sprint Fidelis fractures involve the pace-sense component of the lead, which may cause oversensing of electrical artifacts, undersensing of ventricular depolarizations, and/or loss of ventricular capture. Approximately 10% to 20% of Sprint Fidelis fractures involve the high-voltage conductor, which may compromise defibrillation. The most common clinical consequence of pace-sense conductor fracture is inappropriate shocks, which often occur in painful clusters and without warning.2–4 Inappropriate shocks may be proarrhythmic and lethal,5,6 and patients who experience them may suffer psychological sequelae. ICD lead failures are more likely to result in oversensing than pacemakers because the ICD pulse generators use high-sensitivity amplifiers to effectively detect ventricular fibrillation (VF). In this issue of Circulation , Swerdlow et al7 describe a new algorithm that may avoid or reduce inappropriate shocks and other serious adverse events in patients with failed Sprint Fidelis and possibly other high-voltage leads. If this algorithm proves to be safe and effective, it will be an important advance in ICD therapy. Article p 2122 Fracture of a transvenous high-voltage ICD lead was first observed in the original CPI Endotak model in 1988.8 Patients who had this lead suffered multiple inappropriate shocks, and it was withdrawn from clinical trial. Since then, conductor fractures and insulation disruption have challenged engineers and physicians to develop improved designs and implant techniques. Progress has been made, but not without setbacks. The Medtronic Transvene lead, a coaxial polyurethane design introduced in 1993 and implanted in >24 000 patients, exhibited both insulation degradation and conductor fractures; these failures typically appeared ≥4 years after implant and most commonly presented as inappropriate shocks.9 A mismatch between the terminal …