 Study population will include patients of both sexes included in the Medtronic CareLink Network and implanted with a Medtronic wireless implantable cardiac defibrillator ICD or cardiac resynchronization therapy device with defibrillation capabilities device CRT-D at Hospital Araba former Hospital Txagorritxu. There are approximately 223 ICD and CRT-D patients included in the CareLink Network at this site, and average number of transmissions per month is 80, so it is expected that 480 transmissions are received during the study duration. 