 Socio-demographic and clinical data: For all of the included patients, demographic gender, age, educational level, marital status, country of birth Italian citizens or foreigners, social through a family context survey and clinical classification of HF using the NYHA classification, the implantation date and type of ICD, the execution of and the changes in laboratory tests and electrocardiograms results, number of perceived discharges data will be recorded. Data on the patients diagnosis and possible associated diseases will be obtained through the analysis of clinical documentation and will be record in accordance with the International Statistical Classification of Diseases and Related Health Problems, 9th Revision ICD-IX. 