RELIANCE 4-FRONT, endocardial cardioversion/defibrillation and pace/sense lead, Permanent Defibrillator Electrodes; Model Nos. 0654, 0655, 0657, 0658, 0682, 0683, 0685, 0686, 0692, 0693, 0695, 0696

Affected lead models may experience gradually rising LVSI measurements in association with calcification of the defibrillation lead coils. The issue may lead to early lead replacement. Most serious harm is death or need for cardiac resuscitation.

On July 24, 2025, firm notified physicians via Important Medical Device Information letters. The letter provides information on the management of gradually rising daily subthreshold, low-voltage shock impedance (LVSI) pattern associated with calcification of expanded polytetrafluoroethylene (ePTFE) coated single coil (SC) and dual coil (DC) RELIANCE defibrillation leads manufactured by Boston Scientific Corporation between 2002 to 2021. Letter includes recommendations for routine follow-ups of affected leads, and considerations to take if lead replacement is planned. The firm is not recommending any changes to the scheduled follow-up interval for patients with ePTFE lead models.