The mismatch between patient life expectancy and the service life of implantable devices in current cardioverter-defibrillator therapy: a call for larger device batteries.

In 2005, Bob Hauser published a paper in the Journal of the American College of Cardiology entitled "The growing mismatch between patient longevity and the service life of Implantable Cardioverter-Defibrillators". Now, nearly a decade later, I would like to perform a second look on the problem of a mismatching between ICD device service life and the survival of ICD recipients. Since 2005, the demographics of the ICD population has changed significantly. Primary prevention has become the dominant indication in defibrillator therapy and device implantation is indicated more and more in earlier stages of cardiac diseases. In former larger scale ICD trials, the patient average 5-year survival probability was in a range of 68-71%; in newer CRT-D trials in a range of 72-88%. Due to a progressively widened ICD indication and implantation preferentially performed in patients with better life expectancy, the problem of inadequate device service life is of growing importance. The early days of defibrillator therapy started with a generator volume of 145 ccm and a device service life <18 months. In this early period, the device miniaturization and extension of service life were similar challenges for the technicians. Today, we have reached a formerly unexpected extent of device miniaturization. However, technologic improvements were often preferentially translated in further device miniaturization and not in prolonging device service life. In his analysis, Bob Hauser reported a prolonged device service life of 2.3 years in ICD models with a larger battery capacity of 0.54 up to 0.69 Ah. Between 2008 and 2014, several studies had been published on the problem of ICD longevity in clinical scenarios. These analyses included "older" and currently used single chamber, dual chamber and CRT devices. The reported average 5-year device service life ranged from 0 to 75%. Assuming today technology, larger battery capacities will only result in minimal increase in device volume. Selected ICD patients may further benefit from device miniaturization-but the vast majority may much more benefit from a significant prolongation in device service life. All published cost-effectiveness analyses in ICD therapy show that device costs and device service life are the dominant determinants of the results. The performed "second look-nearly a decade later" revealed that there are still relevant limitations regarding the device service life in current defibrillator therapy. Technical improvements were preferentially transformed into device miniaturization but not into prolonging device service life. But this optimization is strongly enforced. The most feasible solution might be the use of device batteries with larger capacities. The economic burden, mainly caused by non-adequate device service life, may limit the future realization of ICD therapy in a progressively growing patient population. In the former years, physicians and device manufacturers have ignored the patient perspective in defibrillator therapy. However, it is the patient viewpoint that prolonged device service life is much more important than smaller generator size.