The US Food and Drug Administration (FDA) has recommended that patients who have implantable heart defibrillators with Riata1 and Riata ST leads, manufactured by St. Jude Medical, should have X-rays or other imaging alternatives to check for abnormalities in the insulation surrounding the lead, which is a wire attached to the device that is inserted into the heart.

The manufacturer of the leads, St. Jude Medical, recalled them in November 2011 after reports of premature erosion of the insulation around the electrical conductor wires, also called insulation failure. St. Jude Medical, located in St. Paul, Minnesota, had stopped selling the leads in late 2010. According to the company, as of 2011, about 79,000 Riata leads remained implanted in patients in the US.

Riata and Riata ST leads are used to connect an implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) to the heart in order to monitor its rhythms. ICDs and CRT-Ds can detect life-threatening abnormal heart rhythms and deliver an electrical shock to the heart to restore normal heart rhythms. ICD and CRT-D leads typically have layers of insulation surrounding them that protect electrical conductor wires inside the lead.

Insulation failure may cause some of the electrical conductors inside Riata leads to move within or move entirely outside the outer lead insulation. The lead may malfunction and lead to inappropriate or no shock therapy and potentially life-threatening abnormal heart rhythms.

The FDA’s recommendation is supported by several studies that have demonstrated that routine imaging of the leads may detect previously unrecognised abnormalities with the insulation. X-rays or other imaging techniques will help health care providers develop individualized patient treatment plans. The FDA is also cautioning against routine removal of leads without careful evaluation of benefits and risks to the individual patient.

“The majority of Riata and Riata ST leads, including those that show signs of electrical conductor migration or externalization, continue to function normally and provide life-saving support for patients,” said Jeffrey Shuren, MD, director of FDA’s Centre for Devices and Radiological Health. “However, the agency does not have enough information to determine the frequency and timing of insulation failure in these leads; therefore, the post-market surveillance studies will ensure that health care professionals and patients get the data they need to better guide clinical management decisions.”

The FDA is also requiring St. Jude Medical to conduct three-year post-market surveillance studies (or section 522 studies), to collect clinical data related to the potential for premature insulation failure in Riata and Riata ST leads.

The studies must address: the number of patients with evidence of insulation failure and whether the failure was detectable with X-ray imaging; how soon after implantation the lead insulation fails; the time between lead implantation and lead malfunction; and adverse events associated with treatment for failing or malfunctioning leads.

While the current recommendations apply only to the Riata and Riata ST ICD and CRT-D leads, the FDA also is requiring St. Jude Medical to conduct post-market surveillance studies on its: QuickFlex LV CRT leads; QuickSite LV CRT leads; and Riata ST Optim and Durata ICD leads.

CRT devices are small, battery-powered units implanted in the chest of patients to treat heart failure by helping the left and right sides of the heart beat in unison. Like ICDs, CRTs use insulated leads to monitor the heart’s rhythm and to deliver electrical therapy to the heart.

St. Jude Medical voluntarily recalled and stopped selling its QuickSite4 LV CRT leads and QuickFlex5 LV CRT leads in April 2012. These devices were recalled due to insulation abrasion.