Recalled ICD Leads
Abstract & Commentary
By John P. DiMarco, MD, PhD
Source:Krahn AD, et al. Outcome of the Fidelis implantable cardioverter-defibrillator lead advisory: A report from the Canadian Heart Rhythm Society Device Advisory Committee. Heart Rhythm 2008; 5:639-642
In october, 2007, Medtronic, a leading ICD and pacemaker manufacturer, issued an updated lead safety advisory and recalled the Sprint Fidelis family of ICD leads. In this paper, Krahn and colleagues analyzed the Canadian experience with the use of these leads and discuss the implications of their data for patient management.
Twenty-one of 23 adult ICD implant centers in Canada participated in this study. Three pediatric centers, which together implanted 32 total ICDs with a Fidelis lead, were combined as a single center. Lead failure was noted in 80 (1.29%) of 6181 leads at a mean 21 months of follow-up. Lead failure presented with inappropriate shocks due to oversensing of noise on the ventricular sensing circuit in 45 of the 80 patients. In most cases, inappropriate shocks were multiple, with a median of 7 shocks per patients. Oversensing was the primary form of failure in the 60 leads and, as mentioned previously, led to inappropriate shocks in 45 patients. Pacing failure was seen in 10 leads (13%) and high voltage failure in 15 leads (19%). There was more than one type of malfunction in 5 leads. Lead failure was not detected by routine device interrogation during scheduled visits prior to the clinical episodes of failure. The incidence of lead failure was analyzed according to center and according to individual operators. No pattern of significantly higher risk was observed. However, it was noted that 6.2% of the patients from the pediatric centers, as opposed to 1.2% of the adult patients, experienced a lead failure.
Krahn and colleagues conclude that the documented failure rate of Medtronic Fidelis leads is 1.3% at 21 months. The most common presentation is inappropriate shocks due to oversensing. There is no pattern of increased risk associated with individual implant centers or operators.
Commentary
By the time it was withdrawn, the Medtronic Fidelis family of defibrillation leads had been implanted in over 220,000 patients. This lead is a 6.6 French lead that was designed to be easy to implant and have a lower cross-sectional area. However, when a failure rate that was higher than that seen with the previous generation of larger diameter ICD leads from the same manufacturer was noted, an alert was issued and the lead was withdrawn from distribution.
The paper by Krahn et al documents a relatively modest failure rate during the period of study, but these observations only partially deal with the clinical issues involved. The real question is the shape of the failure curve. If the failure rate either flattens or is linear over time, most patients will be unlikely to have a fracture, and a conservative approach, as encouraged here, will best for most patients. However, if the failure rate is not linear but rather increases significantly over time, one could argue that many patients should undergo elective lead replacement. Unfortunately, at this point in time, we cannot be certain what the shape of the survival curve will be, and close follow-up of the aggregate survival data will be very important. Of particular interest, will be the performance at the 4- through 7-year time point. This is the time interval during which many patients will come for an ICD generator change as the device's battery becomes depleted. Since an additional procedure, with the added cost and risk of infection, will not be required, it will be important to know then whether or not the old lead should be replaced when the generator is change.
Although the last wave of ICD advisories were related to potential defects in the pulse generators, leads have long been the weak links in any ICD system. Under the best of circumstances, ICD lead failures are relatively common. The failure rate with the Sprint Fidelis leads is considerably lower than the failure rates seen with all ICD leads just 10 years ago, but the estimated rate is higher than that seen with the previous generation of Medtronic ICD leads. Lead removal, particularly with dual coil ICD leads is much more complicated than just replacing a generator. Both adding another lead and extraction/replacement of a defective lead, run the risk of complications that are higher than that seen with just generator replacement alone.
In october, 2007, Medtronic, a leading ICD and pacemaker manufacturer, issued an updated lead safety advisory and recalled the Sprint Fidelis family of ICD leads.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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