Latent Clinical Outcomes of Appropriate and Inappropriate ICD Shocks

Abstract

Introduction: Despite the proven survival benefits, ICD (implantable cardioverter defibrillator) therapy has still some drawbacks. It is clearly known that inappropriate shocks increase mortality however, randomized controlled trials showed us that appropriate shocks might also increase mortality. Left untreated, ventricular arrhythmias are known to be fatal and in this case ICD shock therapy is life-saving so it is appropriate to assess the effects of ATP (Antitachycardial Pacing) therapy and shock separately. The aim of our study is to determine the effects of inappropriate and appropriate shocks in a population of ICD implanted patients.Patients and Methods: We retrospectively screened ICD implanted patients between January 2003 and December 2013 in our department. Additionally, patients were called by telephone and parameters such as survival and rehospitalization were updated. During the retrospective follow-up, the occurrence of inappropriate-appropriate ICD shocks and mortality causes were noted. Characteristics of patients suffering from shocks were also investigated. Results: A total of 260 ICD implanted patients were included in the study. 40 of them experienced inappropriate shocks (defined as at least one inappropriate shock, not any appropriate shocks). 69 patients experienced appropriate shocks (defined as at least one appropriate shock, not inoppropriate shocks). Retrospective mean follow up period was 49 months, minimum follow up period was 6 months. Among 40 patients experiencing inappropriate shocks 13 deaths (32.5%) occured (p=0.039). Among 69 patients experiencing appropriate shocks 24 deaths (34.8%) occured (p=0.001).Conclusion: In a large cohort of ICD patients, inappropriate and appropriate shocks were common. The most important finding was the association between appropriate shocks and mortality.