Lead Perforation: Incidence in Registries

Abstract

Pacemaker and implantable defibrillator lead perforation, although relatively uncommon, is a recognized potential complication of pacemaker or defibrillator lead implantation. Published event rates range from 0.1% to 0.8% for pacemaker leads and 0.6–5.2% for implantable defibrillator leads.1 Although most perforations are recognized during or shortly after implantation, subacute and late perforations have also been reported. Khan and colleagues reported three cases of late perforation (detected more than one month after implant); two with right atrial and one with a right ventricular pacing lead.1 Subclinical lead perforation may occur more frequently. A recent report showed radiographic evidence for perforation in 15% of both active and passive pacemaker and defibrillator leads discovered incidentally on CT scans obtained for other reasons. Pacemaker and defibrillator lead perforation is often attributed to one or a combination of factors including patient characteristics, concomitant therapies such as steroids or anticoagulants, implant techniques, and the design characteristics of the lead. This issue of PACE includes three case reports describing four patients with late (detected more than 30 days after implant) implantable defibrillator lead perforation involving St. Jude Medical's Riata® ST leads, including three 8-French (F) leads and one 7-F lead.3–5 Like other manufacturers of implantable pacemakers and defibrillators, St. Jude Medical encourages, logs, and tracks all verbal and written reports with respect to any device or lead issue, including perforation. Among returned products and reported incidents involving 121,000 implanted Riata leads in the United States, a perforation incidence rate of 0.086% has been observed. This voluntary field reporting indicates an incidence of 0.057% for 86,000 Riata 8-F leads and 0.157% for 35,000 implanted 7-F leads. Although voluntary reporting is both encouraged and valuable, it may underestimate the true incidence of an adverse event, particularly when the cause of the event may be multifactorial and when, as is often the case for a lead, the device cannot be returned for analysis. In 2004, St. Jude Medical initiated the first of three prospective registries to monitor actively the performance of devices, both leads and pulse generators. Currently, three registries are collecting Riata lead performance data: the Advancements in ICD therapy (ACT) Registry, the Optim™ Lead Insulation Material (OPTIMUM) Registry, and the St. Jude Medical Product Longevity and Performance (SCORE) Registry, The ACT Registry is designed to monitor clinical outcome, including device performance, of patients receiving ICD and CRT-D systems. It has enrolled 5,461 patients with systems implanted at 333 centers by over 400 physicians between November 2004 and March 2006. The ACT Registry follows 4,721 patients implanted with Riata leads, 4,704 of which are 8-F leads and 17 of which are the newer 7-F Riata ST leads. The median follow-up in the ACT Registry is two years and all patients have been followed for over one year. The OPTIMUM Registry is designed to monitor the long-term performance of leads utilizing Optim™, a novel co-polymer that combines the best attributes of the standard lead insulating materials, silicon rubber, and polyurethane, based on bench testing and in vivo studies. The OPTIMUM Registry opened enrollment in August 2006 and as of October 2007, included 2,877 patients at 128 centers with implants performed by 208 physicians. This registry currently follows 1,144 patients implanted with the 7-F Riata lead, of which 220 have been followed for more than one year. The third active registry, SCORE, started enrolling patients in June 2007. It will monitor indefinitely the performance of all implanted St. Jude Medical CRM products at 40 major U.S. centers. Currently the number of Riata leads entered into the SCORE Registry is insufficient to allow for meaningful analysis and inclusion in this report. The lead data provided by these registries are updated, analyzed, and shared with the physician members of the St. Jude Medical Independent Leads Medical Advisory Board on an ongoing basis as recommended by the Heart Rhythm Society Task Force on Device Performance Policies and Guidelines.6 Data from the ACT and OPTIMUM Registries are summarized in Tables I and II. Table I reports the number of patients, centers, and physicians currently participating in the two registries, as well as follow-up duration. Table II shows the incidence of Riata lead perforations reported in the two registries. In the ACT Registry lead perforation was not specifically recorded but rather was included in the single category of lead migration/dislodgment. For the purposes of this analysis, all of the migration/dislodgements reported in the ACT Registry are considered conservatively to be perforations. However, the true incidence of perforations in the ACT Registry is probably lower than what is reported in Table II. As shown in Table II, the incidence of Riata lead perforations in these two prospective studies is 0.33–0.34%. This incidence of perforation is comparable to that observed for standard right ventricular pacemaker leads in patients receiving pacemaker systems and are also followed in the OPTIMUM Registry (0.50% in 1,383 patients; Table II). These perforation rates are also at the low end of what has been reported in the medical literature for defibrillation leads.1 Factors that have been postulated to contribute to late lead perforation are similar to those that are thought to contribute to acute perforation: patient characteristics, concomitant therapies such as steroids and anticoagulants, implant techniques, and the design characteristics of the lead. Of note, in three of the four cases reported in this issue of PACE, the lead was implanted in the right ventricular apex. Kahn and colleagues noted the importance of lead position in minimizing the risk of acute or delayed perforation, suggesting that attempts should be made first to place leads in the septal wall.1 Different leads have different handling characteristics and some physicians vary their implant techniques accordingly. “The importance of ‘understanding anatomy and the nature of one's tools,’ cannot be over-emphasized.”7 In particular, the practice of torquing the lead body after the helix has been fully extended is fairly common, but may contribute to the occurrence of perforations.8 St. Jude Medical has implemented defibrillation lead design changes over time to enhance performance and reliability. The Riata lead included lead body and conductor enhancements designed to reduce the incidence of fractures, and has undergone several iterations including the introduction of Optim™, a novel insulation material designed to enhance handling, abrasion resistance, and long-term performance. Additional design modifications intended to improve ease of use and lead handling for some physicians are being implemented. The data from voluntary returns and complaints analysis and two prospective active registries indicate that both the 7-F and 8-F Riata leads have incidences of perforation within and at the low end of published rates of perforation. In the OPTIMUM Registry, the Riata defibrillator lead perforation rate is lower than that of standard right ventricular pacemaker leads. The reliance on only voluntary reporting of lead perforations in the past makes it difficult to compare the performance documented in today's active registries with that reported for older generation leads. In the future, greater utilization of more sensitive imaging techniques, such as computed tomography scans and enhanced monitoring processes, may increase the detection of these events. The case reports published in this issue contribute importantly to our recognition of the ongoing issue of defibrillator lead perforation. Physicians should continue to bring procedure complications and adverse events to the attention of the clinical community, the companies that manufacture the products involved, and the Food and Drug Administration. Prospective lead registries serve the important role of providing a more accurate estimate of the incidence of lead-related complications and provide perspective to case reports and returned product reports. Through these measures physicians and device manufacturers may identify implant techniques and device designs to further minimize the incidence of these events and improve patient outcomes.