Physicians detailed a case of inside-out abrasion of an Optim-coated Durata lead in an in-press article published online March 25 in HeartRhythm.

Charles D. Swerdlow, MD, a cardiac electrophysiologist at the Cedars-Sinai Medical Center in Los Angeles, and colleagues described a case involving a 78-year-old patient who received an implantable cardioverter-defibrillator (ICD) in December of 2008. The implantation included a St. Jude model 7121 Durata right-ventricular lead, which was extracted in 2013 after incidents of oversensing.

“In our case, the ring-electrode cable abraded against the distal coil, penetrating the ETFE [ethylenetetrafluoroethylene] and shorting to the coil, lowering pacing impedance and generating nonphysiological signals that resulted in oversensing and inappropriate therapy,” Swerdlow and colleagues wrote.

In late 2011, the FDA ordered a Class 1 recall of St Jude’s Riata and Riata ST silicone defibrillation leads due to insulation failures that could cause the ICD lead to malfunction. The Durata lead shares some design features with the Riata leads but has a proprietary Optim coating designed to prevent insulation abrasion.

Robert G. Hauser, MD, of the Minneapolis Heart Institute and colleagues previously had reported that an analysis using the FDA’s Manufacturers and User Device Experience database found cases where 12 Durata leads had can abrasions and six had abrasions caused by friction with another device; 72 percent of those 18 leads had electrical abnormalities. They suggested that Optim may not prevent insulation failures caused by friction.

Swerdlow and colleagues also noted breaches of the Optim tubing. They proposed that cyclical stress and chemical degradation may have caused cracks that then became defects, but they also acknowledged the possibility that defects may have occurred while the lead was explanted.

“It [the case report] illustrates how the tubing does not protect against critical short circuits caused by under-the-shock-coil abrasions,” they concluded. “The pattern of simultaneous, cyclical, nonphysiological signals on both the shock and sensing channels should alert clinicians to the possibility of shorting between the ring cable and distal coil.”

Swerdlow reported that he is a consultant for St. Jude Medical.