**1. Introduction**

The implantable cardioverter defibrillator (ICD) is currently considered the first therapy option to protect patients from life-threatening ventricular arrhythmias. Several random‐ ized studies demonstrated a reduction in total mortality of up to 55% and a reduction in arrhythmogenic mortality of up to 76% in ICD recipients.[1-7] Within a time frame of about 20 years, indications for ICD have evolved from a restricted "last resort therapy" to a secondary and primary preventive therapy. According to HRS/EHRA Expert Consensus on the Monitoring of Cardiovascular Implantable Electronic Devices [8], incidence of ICD implantation in the US and Europe in 2007 was 235,000 and 88,000, respectively, with a upward trend.

Moreover, prevention of sudden cardiac death (SCD) through the ICD is generally consid‐ ered to represent a therapy, which will be needed for the rest of the patient's life. Howev‐ er, regarding ICD cost-effectiveness as well as the potential risks of ICD therapy and subsequent generator changes the question rises if patients without any adequate ICD in‐ tervention during the lifespan of their index ICD really need further ICD protection. Therefore, the question whether or not to replace an ICD generator at the time of battery depletion is of great importance not only for the affected patients but also for their physi‐ cians and cost carriers.

This chapter is aimed to give an overview about the currently published data on long-term benefit of ICD therapy based on the incidence of adequate ICD therapy and in the ratio of potentially serious complications.

© 2013 Erkapic and Bauernfeind; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
