Incidence and risk factors for first and recurrent ICD shock therapy in patients with an implantable cardioverter defibrillator.

One in eight ICD recipients received appropriate shock 2-7 years after guideline-directed implantation. More than one-third of patients with a first shock experienced recurrent shock. Few clinical variables showed potential in predicting shocks, illustrating a need for more advanced tools to select candidates for implantation.