This chapter addresses one of the most controversial aspects of cardiac resynchronization, the need of incorporating defibrillation (ICD) capabilities into resynchronization devices (CRT). As will be described, apart from other more or less marginal arguments, the issue is basically one of cost, since the price of a CRT-ICD is more than three times that of a CRT alone system (CRT-PM). This is a theme that is familiar to electrophysiologists used to debate about the efficiency (or the cost-efficiency) of ICD in primary prevention in the field of resynchronization. Although it is generally accepted that ICD implantation is indicated in patients who have suffered from ventricular fibrillation / tachycardia (class I, evidence level A or B) [1-5], and despite a growing number of clinical trials and its inclusion into the latest guidelines as class I , ICD utilization still is a subject of controversy that has extended to CRT.
Clearly, we are not in possession of a clear and final answer to this question. Moreover, all arguments are based on the assumption of current costs and the performance of currently available stratifiers. In this chapter, we will describe the most relevant evidence regarding: 1) scientific findings on the reduction of mortality with CRT-ICD; 2) the impact on quality of life associated with CRT and ICD; 3) available cost efficiency analyses; and finally 4) the current situation concerning the indications for the defibrillator, as recognized in guidelines, and future perspectives.