UK competent authority the MHRA has issued a medical device alert(MDA) relating to St. Jude Medical’s Bipolar QuickSite and QuickFlex lead models: 1056T, 1058T, 1156T and 1158T. The alert relates to the potential for these leads to suffer externalisation, albeit with less clinical significance than the same problem could provoke in the now infamous Riata and Riata ST cases.
While screening patients identified to be at risk following earlier Riata and Riata ST alerts, the same failure mechanism (lead externalisation) was observed in a small number of QuickFlex/Quicksite leads implanted to provide additional CRT. The potential clinical consequences of these lead failures is significantly less serious than for the Riata leads as there is no risk of loss of high voltage ICD therapy.
Although the prevalence of confirmed cases of externalised cables among QuickFlex/Quicksite leads is currently low (0.023%) a preliminary assessment by the manufacturer estimates that externalized conductors may be present in 3–4% of the patient population.
The MDA states that to date there have been no reports of electrical failure or patient harm associated with externalisation of Quicksite/Quickflex leads.
Externalised cables have been found to continue to function normally due to their inner protective ETFE coating. If, however, the inner coating were to be breached and the system failed to provide alternative pacing therapy, biventricular pacing/CRT therapy could be lost. This could give rise to reduced heart pumping efficiency, reduced ejection fraction, and ultimately an exacerbation of heart failure.
What to do?
Full directions about patient follow-up and resultant actions are provided on the alert which can be found here.
St.Jude Medical has stated that it does not manufacture any other leads which could fail in this manner.