Concerns about the Riata® ST (St. Jude Medical) ICD Lead

In the past year (including three additional case reports in this issue),1-3 reports of perforations with both active and passive fixation St. Jude Medical Riata® ST implantable cardioverter defibrillator (ICD) leads (Sylmar, CA, USA) have appeared in the literature.4-6 In some cases, the authors did not report the event directly either to the manufacturer or to the Food and Drug Administration (FDA), believing they were isolated events. It was only when multiple case reports emerged from different geographic areas and were submitted for publication that editors recognized a problem that seemed to be neither isolated nor rare. Thus, a series of events such as these demonstrates not only the value of case reports, but also underscores the obligation of a physician to report important (particularly adverse) events even when an overall pattern is not yet established. When implantable devices are involved, the importance and value of registries providing long term follow-up and guidance cannot be emphasized strongly enough.7, 8 A review of the MAUDE database reports just 15 cases of perforation with the Riata lead with one reported death; this may be a reflection of underreporting. Now back to the lead. What is particularly troublesome about this lead is not only the perforation but its late presentation. Sometimes the lead perforation does not come to clinical attention until it is well beyond the right ventricular free wall. Furthermore with the Riata, the movement continues until it protrudes out several cm into adjacent tissue. This factor seems to distinguish it from a small perforation in which only the tip of the lead penetrates the right ventricular wall. It could result in ventricular asystole if a patient is pacemaker dependent or in failure to successfully defibrillate, both resulting in sudden death. If perforation does not occur in the first three months, can we stop worrying? We do not yet know the answer to this question. When problems with a lead arise, one first asks, is it operator misadventure or inexperience? Certainly ventricular lead perforation is not a new finding. It is a well-known complication of pacemaker or ICD leads. Too much loop or tension on the lead will predispose to forward movement through the thinner right ventricular wall, particularly at the apex, as recently stressed by Mond.9 When the problem starts happening to even experienced operators around the world, the design of the lead then must be considered. What is different about the lead in question? Manufacturers have attempted to modify lead design to create a smaller diameter lead more resistant to potential crush injury and to allow room for additional leads (e.g., a left ventricular lead) in the already limited space of the subclavian or axillary veins. Modifications have resulted in changes in lead body construction, insulation thickness, and perhaps most important, pressure and stiffness at the tip of the lead. It may be the stiffness of the tip combined with the smaller diameter and forward pressure on the lead that contributes to perforation. And if the operator leaves too much loop, the problem may accelerate. The Riata lead is available in a variety of models including larger and smaller true bipolar or integrated bipolar platinum–iridium leads with a titanium nitride coating. Danik and Mela comment on their use of the newer Riata model leads and have observed three additional cases of perforation.10 Based on their experience, they predominantly now use the larger-diameter model 1591 lead. Other centers have stopped using this lead.6 What then should be the response of the electrophysiology community, the manufacturer, and the FDA? There is a legitimate concern that the problem may be more than physician misadventure and that there may be an inherent design flaw, at least in some of the models of the Riata lead. First, let us not panic either the physician or the patient. We need to collect and analyze the data with the help of the design engineers. Analysis of stiffness, force, and insulation are critical factors. We need careful follow-up of all patients implanted with the Riata family of leads, at three monthly intervals up to 24 months. Physicians who continue to use these leads should be mindful of the potential problem and gently implant the lead with careful technique and without undue tension. All perforations should be reported to the manufacturer and entered in a registry. This issue has been made more acute with the recall by Medtronic (Minneapolis, MN, USA) of the Sprint Fidelis family of ICD leads. Cooperation between the electrophysiology community, the manufacturer, and regulatory agencies should have one goal, the continued safety and care of the patient. Determination of the true incidence of an event requires knowledge of the numerator and denominator. Underreporting complications for whatever reason can be detrimental and may prevent or delay uncovering a trend or significant finding. PACE encourages all physicians who have knowledge of a perforation with this lead or any other lead or device, even if in the past five years, to report the event. The FDA has a website named MedWatch, http://www.fda.gov/medwatch/, precisely for this purpose, to report adverse events/reactions to medications, drug products, or medical devices.