Psychological Indices as Predictors for Phantom Shocks in Implantable Cardioverter Defibrillator Recipients

BACKGROUND: A phantom shock-the sensation of an implantable cardioverter defibrillator (ICD) discharge in the absence of an actual discharge-is a phenomenon that can occur in ICD patients. Little is known about the influence of psychological factors on the incidence of phantom shocks. We evaluated psychological correlates of phantom shocks 2 years post-ICD implant in a cohort of Dutch ICD recipients. METHODS: Consecutive patients (N = 300; 87.5% men; mean age = 62.3) willing to participate in a prospective study (Twente ICD Cohort Study) on psychological factors in ICD recipients received an ICD between September 2007 and February 2010. At baseline, patients complete the 36-item Short Form Health Survey, Hospital Anxiety and Depression Scale, and the Type D Scale. Lifetime presence of anxiety and depression was assessed with the MINI structural interview. RESULTS: During a follow-up of 24 months, 16 patients (5.4%) experienced a phantom shock. Median time to (first) phantom shock was 13 weeks (range 0-48 weeks). In univariable analysis, no significant relationships were found between clinical or psychological indices and the occurrence of phantom shocks, nor was there an association between phantom shocks and type D personality, symptoms of anxiety, or a history of anxiety and depression. CONCLUSIONS: Neither symptoms of anxiety and depression nor psychiatric history were associated with the occurrence of phantom shocks. Further studies using more explorative, qualitative research techniques are warranted to examine the correlates of phantom shocks.