Arrhythmias Detection in a Real World Population

The study is a prospective multicenter registry. Consecutive patients with indications of implant / replacement or upgrade of implantable cardioverter defibrillator (ICD) will be enrolled. The primary objective of the study is to determine the predictors of appropriate anti-tachycardia therapy (with shock) in a non-selected population of patients implanted with an ICD. Secondary objectives of the study are: * the incidence of anti-tachycardia therapies; * the predictors of inappropriate therapy and onset of arrhythmia burden; * the adherence to the current guidelines in the Italian clinical practice; * the predictors of heart failure (HF) onset and response to cardiac resynchronization therapy (CRT).