“the appearance of an externalized conductor alone should not provoke an overreaction”
As long ago as December 19th we reported on FDA’s classification of St Jude’s recall of it’s Riata implantable defibrillator leads. Now a meeting has been held between an esteemed group of clinicians and St Jude staff to discuss the ongoing situation. The meeting content was recorded by one attendee, Dr Edward J Schloss, and can be found on US site Cardiobrief here.
From the notes of Dr Schloss, reportedly sixty-three registered health care professionals and St. Jude Medical industry representatives gathered at the end of last week at the Minneapolis Airport Marriott Hotel for what was entitled “the Riata ICD Lead Summit”. The conference, organized by The Minneapolis Heart Institute Foundation and Mayo Clinic, was organized to review available data and develop a consensus regarding St. Jude ICD leads currently on recall or subject to increased scrutiny. This is in view of the fact that “lead cable externalisation” in St Jude’s Riata implantable defibrillator patient population remains an issue requiring management by the cardiology community.
Clinician opinion poll
Conference attendees were first polled about the current landscape and results showed that 35% thought Riata leads posed a greater concern to them than the Medtronic Fidelis issue, also reported in our pages as long ago as February 2009. In addition, 41% felt enough concern about the currently marketed Durata lead that they have elected not to implant this lead. The Durata lead, although not on recall, shares many design elements with the Riata ST.
Clinical and engineering data were also analysed by the group. “The failures of Riata leads appears to be due to a unique “inside-out” form of lead insulation abrasion. In some, but not all cases, lead cables have been shown to externalize. Commonly, however, externalization is not associated with failure and vice versa. There is no single common sign of lead failure on electrical measurements.”
Furthermore significant discussion took place regarding bench data supplied by St Jude engineers who reportedly “admonished” the group saying “the appearance of an externalized conductor alone should not provoke an overreaction.” This was based on the finding that in bench testing, externalised leads demonstrated normal function.
Clinical significance questioned
The group discussed the clinical significance of lead externalisation, in view of the fact that two centres showed different externalisation rates of 15% and 25% respectively, while agreeing that “leads with externalized conductors commonly have normal electrical performance.”
Prophylactic removal not recommended
On the subject of lead extraction there was a strong consensus that it may be difficult and that removal should therefore not be prophylactically undertaken. Diagnostic strategies were discussed, speakers agreeing that detection of failures has been challenging given the varied and sometimes subtle changes seen.
Second poll suggests lack of clinician reassurance
Perhaps surprisingly, at the end of the meeting the poll was repeated and on this occasion a higher proportion of respondents expressed their concerns. In fact 44% indicated that they had enough concern about the newer Durata lead (referenced in St Jude statement below) that they would not be using this in the future.
55% of attendees favoured routine repeated fluoroscopic monitoring.
St Jude’s post meeting statement
Subsequent to the meeting St Jude has issued a statement pouring cold water on the results of the second poll, claiming that the group was small and therefore unrepresentative and furthermore that a number had left the meeting prior to the second poll. The statement, which can be found here goes on to say that St Jude’s newer iteration device, the Durata lead, possessing features which prevent externalisation has “demonstrated excellent results by any measure”. This no doubt in response to meeting organiser Dr Robert Hauser stating that Durata should be “put under the microscope”.