Defibrillation Failure with an Electrical Short Circuit Caused by Internal Insulation Breach

St. Jude Medical (now Abbott) released the Riata ST Optim lead in 2006 as one of the Durata family of defibrillator leads. These leads were coated with silicone polyurethane copolymer insulation material (Optim) on Riata and Riata ST leads. In 2011, Riata and Riata ST leads were designated to be a class I recall by the United States Food and Drug Administration (FDA) because of lead insulation failure. Since the Riata ST Optim lead increased the insulation thickness by 50% after coating with 0.09-mm Optim,1 the rate of conductor externalization was significantly decreased, from 19%–28% in Riata and Riata ST leads2 to 19,000 patients in the United States and the 10-year survival rate is approximately 92%, according to an Abbott product performance report.4 However, in contrast to improvement of conductor cable externalization, concerns of internal insulation breach, a possible cause of silent lead malfunction or defibrillation failure, remain to be determined. Herein we report a case of defibrillation failure with a lack of effective shock delivery owing to low defibrillation lead resistance (<20 Ω) in a Riata ST Optim lead, which was not revealed by routine periodic interrogation.