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A changing scenario in the clinical use of implantable defibrillators: the need for long-term data on lead performance

Giuseppe Boriani, Mauro Biffi, Alessandro Marziali, Igor Diemberger, Cristian Martignani
DOI: http://dx.doi.org/10.1093/europace/eun339 1-3 First published online: 16 December 2008

The story of electrical therapies for the heart began 50 years ago, with the pioneering experience of Senning and Elmqvist, who implanted the first pacemaker at Karolinska hospital in Stockholm on 8 October 1958.1 Since then electrical therapies have undergone an impressive technological evolution with important implications on the clinical use of electrical devices and the outcome of implanted patients.

Two clinical steps in the evolution of electrical therapies were the conception and the clinical validation of implantable cardioverter defibrillators (ICDs) and devices for cardiac resynchronization therapy, which have extended the benefit of treatment with electrical devices to a much wider proportion of patients affected by heart diseases.1,2

The treatment with ICDs was conceived more than 30 years ago as a last-resort intervention for highly selected patients who had survived at least two episodes of cardiac arrest.2 In the first years after its approval by the FDA in 1985, the overall number of ICD implantations thus remained low, both in the US and Europe.2 In the last decade, the scenario of clinical use of ICDs changed dramatically and randomized clinical trials have prompted a widening of clinical indications, with a shift towards increasing use of ICDs in the setting of primary prevention of sudden cardiac death, for patients identified as subjects at increased risk for life-threatening ventricular tachyarrhythmias.3,4

The changing scenario has taken into consideration ICD implantation in categories of patients in whom the arrhythmic risk is the major determinant of an adverse outcome, or even represents the only determinant of an adverse outcome, thus with the potential for a ‘normal or near-normal’ patient life expectancy after implantation of a life-saving reliable ICD system. Indeed, in the last 10 years, ICD implantation has been proposed and actually performed in selected patients affected by hypertrophic cardiomyopathy, arrhythmogenic right ventricular disease, Brugada syndrome, idiopathic ventricular fibrillation, ventricular non-compaction, arrhythmogenic congenital heart diseases, etc.,3,5 thus modifying, at least in part, the demographics of ICD recipients, as well as extending the length of expected ‘marriage’ between the patients and the device system (generator and leads).6

As a result of an evolving and changing scenario with regard to clinical use of ICDs, two basic characteristics of the ICD system, generator longevity and long-term performance of the leads, have gained much more relevance in comparison to the first 10–15 years of ICD use, becoming critical determinants of long-term performance. In view of the high demands placed on ICD performance, it is quite easy to understand that any reported malfunction of the ICD system (generator and/or leads) may provoke important and emotional reactions, not only within the medical community and in scientific journals, but also within the public opinion and in the media. This happened in October 2007, at the time of withdrawal of the Sprint Fidelis lead from the market, as spontaneously decided by the manufacturer because of its propensity to fracture. At that time, the information provided by the media was much more catastrophic than what was reasonable to report, generating a great deal of concern among the patients.7 Moreover, similarly to what happened with previous device recalls and advisories,810 this catastrophic news had some negative influence on the confidence of patients and referring physicians regarding the reliability of ICD systems, thus leading to a reduction in referrals from physicians for device implantation, as well as more reluctance on the part of the patients to undergo device implantation when suggested.

Considering the complexity of the scenario that involves not only patients and physicians, but also device and lead manufacturers, regulatory agencies, scientific associations, patient or consumer associations, the media and public opinion, the initiative proposed by Goette et al.11 in this issue of Europace has to be highly appreciated and merits great attention. As the authors stress, the reporting of ICD lead performance is currently inadequate, with available data derived from some registries, such as the Bilitch registry, the Danish Pacemaker and ICD registry, the United Kingdom Pacemaker and ICD registry or derived from collected series of patients,1214 with no availability so far either of a European or of a worldwide registry on ICD leads. Registries appear the most feasible way for assessing long-term performance of ICD leads. Apart from randomized controlled trials, even available observational studies, planned for assessing ICD effectiveness, suffer from a relatively limited time horizon. In the systematic review reported by Ezekowitz et al.,4 the median follow-up of a series of 53 observational studies was 28 months (inter-quartile range 19–48 months). Goette et al.11 promote the institution of a European registry on ICDs and leads, as a common effort of the European Heart Rhythm Association, the European Society of Cardiology, the industry, European regulatory bodies and representatives of the European Union Commission. The broad perspective of such a proposal appears topical and may represent a challenging opportunity for European cardiologists. A potential question that could be addressed regards the opportunity to have a registry limited to Europe, rather than initiatives aimed at finding a convergence with similar projects in North America, where data on lead performance will be part of the National Cardiovascular Data Registry (NCDR) ICD Registry.14 In the practice of cardiac electrophysiology, differences can be found not only comparing Europe as a whole and North America, but also taking into account the various European countries, where marked variations can be found in implant rates of single-chamber, dual-chamber, or biventricular ICDs, the proportion of large- vs. small-volume centres, involvement in the implantation procedure of cardiologists in training, scheduling of post-implantation follow-up visits for ICD system surveillance and the degree of implementation of remote monitoring for ICD follow-up.15 Moreover, even after a definite diagnosis of lead failure, management may not be homogeneous, with different access to the techniques of lead extraction.16 For these reasons, a registry focused on assessment of the performance of ICD leads in the various contexts of electrophysiological practice in Europe appears to be extremely interesting and appropriate. Indeed, the approach to the problem of lead reliability has to based on a broad perspective, since lead failure is not only linked to mechano-electrical technological aspects, but is the result of a complex interaction of technological lead-related factors, biological and anatomical patient-related factors, as well as implantation-related physician-dependant factors.14 Improved knowledge of the long-term performance of the various ICD lead systems in ‘real-world clinical practice’, and of the variable weight of factors conditioning lead failure may be the way for a more realistic approach to ICD implantations. This may make it possible to provide more appropriate information to the patients and their relatives at the time of the pre-implantation consent form, thus potentially limiting legal litigations related to unrealistic expectations or misunderstandings. It may also allow a more realistic approach to economic evaluations, a crucial step in ICD therapy adoption in the community setting.2,17 As is known, economic estimates imply modelling, based on prediction of future events, including complications and interventions for malfunction of ICD generator or leads. Lead revision or extraction are costly procedures that may markedly affect the cost-effectiveness estimates of ICD treatment.4,18 More precise data on lead performance may therefore provide more accurate estimates of ICD cost-effectiveness, with the potential for an improved evaluation of ICD therapy affordability in the community setting.

As a final comment, the proposal by Goette et al.11 is a crucial step towards optimization of treatment with ICD systems. Nowadays, clinical use of any treatment or intervention requires following the so-called ‘great circle of patients’ care' where application of evidence-based guidelines in ‘real-world’ practice is not the point of arrival but just a step, during which performance and outcomes are monitored and analysed, with the aim of continuously re-assessing the actual results of applied treatments and, if necessary, modifying the applied interventions, if something is defective, in order to improve the overall quality of care delivered to the patients.19 Trying to improve the quality and reliability of our treatments is of special added value for complex and expensive treatments such as ICDs, which involve great expectations on the part of the patients, the medical community, and the society. The changing scenario we are facing prompts the need for an evolution in the ways we test, develop, and monitor therapeutic interventions, but also requires combined and hopefully synergetic efforts of physicians, patients, scientific associations, patients and patient associations, the industry, regulatory agencies, policymakers, and healthcare administrators.

Conflict of interest: none declared.

Footnotes

  • The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.

References

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