The prevalence and incidence of heart failure are progressively increasing in both Europe and the United States. Despite many advances in diagnosis and therapy, morbidity and mortality remain high and long-term prognosis is still poor in most heart failure patients. The use of implantable devices, cardiac resynchronization therapy and implantable cardioverter-defibrillators plays a pivotal role in the treatment of heart failure. Cardiac resynchronization therapy improves survival and reduces cardiac mortality due to either sudden or non-sudden death. In clinical practice, patients with an indication for cardiac resynchronization therapy should be carefully evaluated in view of a potential concomitant indication for defibrillator implantation. The combination of the two therapies may have maximal beneficial effects on prognosis.