Longevity of implantable cardioverter-defibrillators: still a long way to go

This editorial refers to ‘Battery drain in daily practice and medium-term projections on longevity of cardioverter-defibrillators: an analysis from a remote monitoring database’ by G. Boriani et al., on pages 1366–1373. This issue of EP-Europace features an important study by Boriani et al.,1 which shed lights on the expected longevity of cardioverter-defibrillators (ICD). The data behind the results stem from a single manufacturer-specific remote follow-up database, and the findings thus only are applicable to recent defibrillators from this manufacturer. In general, the results confirm the projected medium-term estimates of longevity of these devices as provided by the manufacturer. With these devices ‘medium terms’ means 3–5 years, as the projected longevity is 10 years for CRT-D and 12 and 13 years for dual- and single-chamber ICD. Critics may infer that the study is only a short- to medium-term study and that the results confirm only similar short-term projections, whereas long-term results are lacking. In addition, the present data represent predicted battery longevities, and not real-life device longevity. Recent studies indicate a markedly lower real-life ICD longevity of especially cardiac resynchronization therapy (CRT) ICDs that differs significantly between manufacturers.2 The future will show us whether the longer predicted longevities in the devices studied by Boriani et al. are correct. Shorter predicted longevity was associated with higher pacing amplitudes and more capacitor charges. These findings furthermore support that ICD programming to avoid shock delivery as studied in the MADIT-RIT trial (Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy)3 should be recommended, also to prolong device longevity. It is still unknown whether the use of auto-capture features, which may reduce pacing amplitudes significantly when compared with amplitudes observed in this study, affects predicted longevity. Unfortunately, the study by Boriani et al. does not provide data on the use of auto-capture. The ICD technology is well known and has undergone relatively minor developments in the recent years with remote follow-up and the totally subcutaneous ICD as the exceptions. The battery technology has evolved, but so has the tendency to make the devices smaller and thus also the volume available left for housing the battery.4 What if patients scheduled for ICD implant were asked whether if they would prefer a smaller device or a slightly larger device with an increased battery capacity? The manufacturer and the medical community have had their focus of attention on the continuing issues with the weak part of the ICD system, the defibrillator leads. However, recent results have clearly demonstrated that patients undergoing device replacements have a higher risk of complications than previous anticipated.5,6 This goes for, for example, infection and lead-to-can abrasion. Replacing an ICD is not just about having the newest and smallest updated technology implanted in the simplest device operation. Each replacement procedure poses substantial risk that is far from negligible. Therefore, prolonging the intervals between trivial device replacements caused by battery end-of-life is crucial to reduce the risk of complications. This is especially important since the current patient population have a longer life expectancy when compared with the life expectancy observed in the original landmark ICD trials. Today's ICD population may therefore experience ICD replacements more often and are thus more susceptible to related complications with a substantial reduced quality of life (QOL) and increased economic cost. Wilson et al.7 discussed strategies to reduce infections during the cardiac implantable electronic device implant. One strategy which has not been given sufficient attention in the editorial is a reduction of reoperations, as device replacements and upgrades are significant prognostic factors for device-related infection. In this light, choosing devices with as long battery service as possible for implant is an equally important strategy for reducing device-related infections. From this perspective, real-life results on device longevity are welcomed, drawing attention to longevity as an important factor in choosing the best device for each individual patient. When Boriani et al. compared the medium-term estimated battery life of the CRT-Ds with the expected remaining longevity in the subgroup of patients with severe heart failure, they found that only one-third of patients was likely to need device replacement. Apart from the pure patient perspective and risk of complications related to the replacement procedure, the economic issue also is important. It is not rocket science to appreciate that shorter battery life results in more frequent replacement procedures and thus higher costs. In Denmark, replacement procedures constituted 45% of the total number of all first defibrillator implants in 2015. In a time of economical restraints, reducing the number of trivial replacement procedures by implanting devices with better longevity is highly meaningful. Studies on cost-effective analysis of ICD longevity may also further highlight the economical aspect. The data behind the results provided by Boriani et al. are captured by the remote follow-up system. This is a unique and valuable source of data and this method of obtaining real-life data is a simple yet achievable way of collecting large datasets. However, this opportunity has not been explored extensively so far, and manufacturer-generated data on real-life device longevity are unfortunately sparse. A warranty issued by the manufacturer based on bench-test estimates and a granted compensation if the promise is not fulfilled are reassuring at the time of purchasing. Still, patients would be better off in the long run if the projected longevity data are continuously monitored based on active follow-up. Longevity of new devices cannot be predicted from previous models. The current product performance reports with survival probability are based on returned product analysis that consequently only represents a small fraction of the real-life device performance. In case the longevity estimates in the product performance reports were confirmed by data from remote follow-up, actual and accurate data on device longevity could be provided. A special European issue is that the device technology is often brought earlier to the market in Europe than in North America. This may impose a delay in detecting problems with product performance as the majority of product performance reports from the manufacturer are based only on data from the USA. Multicentre studies of head-to-head comparison of longevity of devices are sparse, but fortunately, a number of these have appeared in this journal.2,8,9 Besides from requesting better data on longevity, the stakeholders in medical community should also ask manufacturers for devices with better battery technology yielding prolonged longevity. This may come at a small price if the volume of the device increases. Conversely, there is no study showing that a reduced volume of a defibrillator results in a better QOL for the patient. It is claimed that the strive to produce small diameter defibrillator leads that resulted in the Medtronic Sprint Fidelis and St Jude Medical Riata leads recalls was a result of demands from the market, i.e. the physicians. It is not known whether there is any similar popular demand behind the development of creating smaller and smaller devices, but let us not repeat previous mistakes by craving products with features that do not necessarily have any clinical benefit on the cost of improved device longevity. The study by Boriani et al. will hopefully prompt the reader's attention towards the longevity issue in ICD therapy, as it is a key factor in long-term patient management, and patients will be better off with longer-lasting batteries. Conflict of interest: none declared.