United Kingdom regulator, the Medicines and Healthcare products Regulatory Agency (MHRA), just issued a warning over St. Jude Medical, Inc.’s QuickSite and QuickFlex defibrillator leads.
The problem, said the MHRA, concerns St. Jude Medical’s Bipolar QuickSite and QuickFlex left ventricular (LV) cardiac resynchronization therapy (CRT) leads; models 1056T, 1058T, 1156T, and 1158T are involved. There are risks of worsening heart failure symptoms due to wear and/or abrasion of lead insulation after implantation, the MHRA explained. St. Jude Medical stated that it is informing physicians about visual observations of externalized conductors on the silicone end of QuickSite and QuickFlex Left-Ventricular (LV) Leads, used to connect Cardiac Resynchronization Therapy (CRT) devices to the heart.
In December 2010 and December 2011 the MHRA issued Medical Device Alerts concerning SJM’s Riata and Riata ST ICD leads, which were experiencing abrasion of silicone, leading to the externalization of cables. During patient screening, the same failure was seen in some QuickFlex/Quicksite leads. Two reports of externalized cables have been received in the UK.
An externalized conductor occurs when the cable/conductor within the lead wears through the outer silicone insulation and appears outside the insulation body. This can be seen on an x-ray or fluoroscopic image. Because these cables are protected by another insulation layer, they can continue to function properly should externalization occur, explained St. Jude Medical.
In the United States, there have been no reports of patient injury or loss of therapy due to externalized conductors in these leads; however, St. Jude Medical will no longer sell these lead models and has confirmed 39 cases of externalized conductors, out of 171,000 sold worldwide. Based on an analysis of leads returned to the company and recent fluoroscopic images of implanted leads still in clinical use, St. Jude Medical estimates that three-four percent may exhibit externalized conductors.
An LV lead is a thin, coated wire that is placed on the lower left chamber of the heart (the left ventricle) to stimulate both sides of the heart to beat in synchronization, which helps the heart to beat more efficiently. LV leads are meant to improve the efficiency of the heart in patients with heart failure and do not deliver immediate life-sustaining pacing or life-saving defibrillation therapy. If an LV lead were to fail, the other leads attached to the patient’s device would continue to deliver life-saving therapy.
In addition to St. Jude Medical’s Field Safety Notice, the MHRA issued a series of recommendations, which indicate, in part, that the recalled bipolar QuickSite or QuickFlex lead models be taken out of use, quarantined, and returned to St. Jude Medical. All patients implanted with the recalled Quicksite and Quickflex devices should be identified, contacted, and scheduled for a follow-up within three months. Details of the MHRA’s clinical recommendations can be accessed here.