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Acute complications resulting from permanent pacemaker implantation are well known and include perforation of the right atrium or right ventricle. With the current high-standard safety parameters of pacing leads, maintaining safety and reliability is crucial and, when they appear, new innovations must withstand safety tests. The Medtronic CapSureFix SureScan 5086 magnetic resonance imaging (MRI) transvenous lead (Medtronic Inc., Minneapolis, MN, USA)—a modified version of CapSure-Fix Novus 5076 lead—has been specifically designed to function in the MRI environment and, due to its wider wire diameter, it is overall slightly larger than its predecessor. The 5086 MRI lead's increased diameter and stiffness are its main drawbacks and may result in a greater risk of implant complications.

Previous experience and initial data suggest that this new lead is safe and may allow pacemaker patients to undergo MRI.[1-4] As a result, in early 2011, the U.S. Food and Drug Administration (FDA) approved it as the first pacing system designed to be used during MRI examinations, and currently the 5086 MRI lead is largely utilized worldwide with an estimated >100,000 implanted leads in the U.S. market alone. Somewhat surprisingly, in this issue of Pacing and Clinical Electrophysiology, Elmouchi et al.[5] report an unacceptable high rate of lead complications in 65 consecutive patients implanted in their center with a Medtronic 5086 MRI lead. The investigators compared their experience with another lead model (Medtronic 5076 lead) implanted in 92 patients during the same period of time. The most concerning data reported are the high rate of subacute lead perforation observed in patients implanted with 5086 MRI leads, resulting in one case to death. This is a new and unexpected finding that points to important questions regarding the safety of this lead; however, at the state of current evidence, caution is compulsory in analyzing the situation.

Consistency of Data: Absence of Evidence or Evidence of Absence?

  1. Top of page
  2. Consistency of Data: Absence of Evidence or Evidence of Absence?
  3. MRI-Relabeled Pacing Leads: Here We Go Again
  4. Conclusions
  5. References

The above-mentioned difference in implant complications between 5086 and conventional pacing leads is in contrast with the results of two postmarket studies and two large multicenter trials. First, two single-center, nonrandomized studies[1, 2] provide a direct safety and efficacy comparison between the newly designed Medtronic MRI-compatible pacing system with conventional implant outcomes. These studies did not report any lead-related death or perforation in 89 patients implanted with 5086 MRI leads. Although these studies suggest an even higher surgical revision due to 5086-lead dislocations, no relevant differences in acute lead performance have been detected between 5086 MRI and conventional pacing leads.

Moreover, two large multicenter randomized studies evaluated the 5086 MRI lead by comparing outcomes in 727 patients with and without exposure to a single investigational protocol MRI scan.[3, 4] Secondary study objectives also included system-related adverse events. Among all enrolled patients, cardiac perforation and pericardial effusion occurred at the same rate of 0.68%; far less compared to the results reported by Elmouchi et al. Furthermore, none of the deaths that occurred during the course of the trials was related to the MRI pacemaker system.

Summarizing the published data, the extraordinary high procedure-related complication rate reported by Elmouchi et al. is clearly in contrast with the current literature. Although reported rates of perforation underestimate the public health burden due to dependence on voluntary reporting, over 100,000 Medtronic 5086 leads have been implanted in the United States only, and this study is the first warning of 5086 lead perforation appearing in the literature. Shall we start worrying? We do not know the answer yet. The cardiology community is no stranger to controversy and contradiction; it is only when many cases emerge from different geographic areas that the problem seems to be neither isolated nor rare. When clinical studies come to opposing conclusions, a careful evaluation is mandatory to determine whether these apparent contradictions can be reconciled.

From one side, we have 816 patients implanted with 5086 MRI leads enrolled in two worldwide-randomized trials and in two smaller single-center studies. So, what can explain the apparently opposed results of the present analysis? The investigators have found no definite explanation for these findings; all operators were very experienced and well instructed on proper 5086 implant techniques. The discrepancy in perforation rates among this study and the previous series likely reflects interplay among a number of complex factors mainly represented by differences in endpoints, intensity of monitoring during follow-up, and procedural technique. Every treatment has a myriad of potential complications, and this article uses a “post hoc” combined endpoint much broader than the previous series. To gain statistical advantage, we often combine end points; however, assembling different endpoints might result in wrong conclusions. For example, the combined endpoint of the study included also chest pain suggestive of pericarditis. This symptom might have been underestimated in previous reports; there are at least three pericarditis-like chest pains without effusion noted in this analysis, and none of them required neither intervention nor lead revision. Are they really lead-related complications? If we consider only overt perforations, only five patients (7.7%) had either pericardial effusions or cardiac tamponade; this is still a high number but the differences between the two groups become nonstatistically significant. The authors, therefore, look at lead complications in different ways, and their results cannot be easily compared with others. Nonetheless, it may be unwise to make decisions about the overall safety of these leads based on the likely insufficient data; reduced awareness of a potential danger could cost a patient's life.

Medtronic 5086 MRI Lead: Not Risk-Free but Safe Enough?

Such a series of events, described by a highly experienced institution, underscores the obligation to monitor carefully this lead in order to evaluate if it can be safely and effectively used for cardiac pacing. On December 2008, at the Policlinico Tor Vergata in Rome, we implanted our first 5086 MRI lead, and we had the first safety concerns in 2011 after an unusual case of a near-fatal late cardiac perforation.[6] Therefore, we felt compelled to review our experience with the newer lead. From an analysis on 240 consecutive patients implanted with MRI-conditional leads, four cardiac perforations occurred.[7] Although three of them were related to a 5086 MRI lead, this finding was not statistically significant; besides, due to the small number of leads of each type, we did not conclude for even a simple trend showing an increased risk of cardiac perforation in patients implanted with this new lead. Anyway, as perforation rate in our laboratory is less than 0.5%, we were concerned about the three lead perforations that occurred in 120 patients implanted with 5086 leads. As a result of a possible dissatisfaction with the 5086 lead, we gradually replaced it with the new MRI-relabeled Medtronic leads (models 5076, 4074, and 4574). These leads have proven reliability given by the longtime use and may prompt more widespread and safe use for MRI-conditional leads.[8]

One additional finding deserves our attention. Elmouchi et al. cite the Medtronic CRDM Product Performance database reporting 99 cardiac perforations and 112 lead dislodgments over 102,899 Medtronic 5086 MRI-registered U.S. implants. Even though the use of reporting rates as measure of risk has several limitations, it is worthwhile to note that among over 1,511,222 registered U.S. implants with the 5076 lead model, 150 cardiac perforations and 470 lead dislodgements have been reported. An observation must be interpreted with caution; accepting a small difference in baseline characteristics between cohorts, it is noteworthy that cardiac perforation rate is approximately 10-fold higher in 5086 MRI leads. Data not only from centers with extensive experience in pacemaker implant but also from real-world experience are needed to comprehend the magnitude of the problem fully.

MRI-Relabeled Pacing Leads: Here We Go Again

  1. Top of page
  2. Consistency of Data: Absence of Evidence or Evidence of Absence?
  3. MRI-Relabeled Pacing Leads: Here We Go Again
  4. Conclusions
  5. References

Lead technology is unquestionably developing fast, and some of the current limitations are going to be resolved. The major companies have recently marketed additional MRI-conditional pacing leads. However, to date, only the Medtronic 5086 MRI lead has obtained FDA approval, whereas other products have Conformité Européenne (CE) marks.

More recently, a series of lead models previously approved for use in non-MRI environment has been tested and relabeled as MRI-conditional. These leads might be preferred by physicians because of their small size, easy handling, and proven reliability. CE mark approval has since been given to the 5076 MRI Medtronic lead and to the CapSure Sense MRI passive-fixation leads (models 4074 and 4574). The latter are the Medtronic's most frequently implanted pacing leads with more than 2.8 million implants worldwide and have demonstrated high reliability over years. In addition, CE mark approval has been achieved by St. Jude Medical (St. Paul, MN, USA) for its Tendril lead as well as Biotronik (Berlin, Germany) for its ProMRI lead and for Boston Scientific (Natick, MA, USA) Fineline-II pacing leads. Since we must be cautious in light of the historical problems manufacturers have had with new leads, the use over several years and the large amount of data on very popular lead models relabeled as “MRI-conditional” allow us to overcome the concerns about safety and lead performance.

Conclusions

  1. Top of page
  2. Consistency of Data: Absence of Evidence or Evidence of Absence?
  3. MRI-Relabeled Pacing Leads: Here We Go Again
  4. Conclusions
  5. References

Does this series represent only an exceptional isolate finding or a worrisome sign? At this time, evidence best supports for the safety of this lead; however, data from additional studies are needed before drawing any firm conclusions. We are facing, once again, that no pacing lead is perfect and without limitations. The importance of communication among physicians as well as between physicians and manufacturers cannot be overstated; careful postimplant evaluation of patients with 5086 leads should continue, and we must form networks for collecting data as part of large lead registries.

References

  1. Top of page
  2. Consistency of Data: Absence of Evidence or Evidence of Absence?
  3. MRI-Relabeled Pacing Leads: Here We Go Again
  4. Conclusions
  5. References
  • 1
    Forleo GB, Santini L, Della Rocca DG, Romano V, Papavasileiou LP, Magliano G, Sgueglia M, et al. Safety and efficacy of a new magnetic resonance imaging-compatible pacing system: Early results of a prospective comparison with conventional dual-chamber implant outcomes. Heart Rhythm 2010; 7:750754.
  • 2
    Wollmann CG, Thudt K, Vock P, Globits S, Mayr H. Clinical routine implantation of a dual chamber pacemaker system designed for safe use with MRI: A single center, retrospective study on lead performance of Medtronic lead 5086MRI in comparison to Medtronic leads 4592–53 and 4092–58. Herzschrittmacherther Elektrophysiol 2011; 22:233236, 9–42.
  • 3
    Wilkoff BL, Bello D, Taborsky M, Vymazal J, Kanal E, Heuer H, Hecking K, et al. Magnetic resonance imaging in patients with a pacemaker system designed for the magnetic resonance environment. Heart Rhythm 2011; 8:6573.
  • 4
    Rod Gimbel J, Bello D, Schmitt M, Merkely B, Shwitter J, Hayes DL, Sommer T, et al. Randomized trial of pacemaker and lead system for safe scanning at 1.5T. Heart Rhythm 2013; 10:685691.
  • 5
    Elmouchi DA, Rosema S, VanOosterhout SM, Khan M, Davis AT, Gauri AJ, Finta B, et al. Cardiac perforation and lead dislodgement after implantation of a new MR-conditional pacing lead: A single-center experience. Pacing Clin Electrophysiol 2013; 37:410.
  • 6
    Forleo GB, Zeitani J, Perretta T, Della Rocca DG, Santini L, Simonetti G, Romeo F. Acute left hemothorax as a late complication of an active-fixation pacemaker lead. Ann Thorac Surg 2013; 95:10811084.
  • 7
    Forleo GB, Della Rocca DG, Panattoni G, Schirripa V, Sergi D, Magliano G, Tesauro M, et al. Clinical and electrical performance of currently available MRI-safe pacing systems. Do all devices perform in the same way? Int J Cardiol 2013; 167:23402341.
  • 8
    Santini L, Forleo GB, Santini M. World society of arrhythmias. Evaluating MRI-compatible pacemakers: Patient data now paves the way to widespread clinical application? Pacing Clin Electrophysiol 2013; 36:270278.