Implantable cardioverter defibrillators (ICDs) are designed to deliver shocks in the event of ventricular arrhythmias. Some ICD recipients experience the sensation of ICD discharge in the absence of an actual discharge (phantom shock, PS).

The aim of this study was to evaluate the incidence, predictors, and consequences of PS in ICD recipients.

Consecutive ICD recipients were examined during a routine outpatient follow-up (FU) visit. Subjects completed a written survey; their level of depression and anxiety was assessed with the hospital anxiety and depression scale (HADS). Quality of life (QOL) was assessed using the Minnesota living with heart failure questionnaire.

Of 434 patients invited to the study, 423 (97.5%) ICD recipients agreed to and completed the survey; 349 (83%) had a primary prevention indication and 339 (80%) ischemic cardiomyopathy. A total of 27 patients (6.4%) reported a PS during a mean FU of 64 ± 44 months (5.4% in the primary prevention group and 10.8% in the secondary prevention group; p = 0.11). PS were related to higher education (≥bachelor’s degree 41% versus 20%; p = 0.03), and more frequent in patients receiving adequate shocks during FU (34% versus 0.5%; p < 0.001). HADS score levels were higher following PS (15 ± 6 versus 8.8 ± 7.4; p < 0.001). The majority of patients reporting PS felt that the information provided to them prior to ICD placement was insufficient (22.2% versus 5.0%), that they needed psychological support after ICD implantation (26% versus 3%), and considered ICD deactivation in near end-of-life situations (59% versus 29%; p < 0.001 for all).

PS occur in 6.4% of all ICD recipients and are related to higher education and to patients that experienced adequate shocks during FU.