Phantom shock in cardiac patients with an implantable cardioverter defibrillator

Upon detecting abnormal heart rhythms, an implantable cardioverter defibrillator administers defibrillatory shocks restoring normal heart function. Patients sometimes report a shock without objective evidence of having received one. Such events are termed phantom shock. Our exploratory, mixed-methods study aimed to gain an understanding of the phenomenological experience of phantom shocks. We tested the hypothesis that phantom shocks are related to an increased level of posttraumatic stress disorder (PTSD) symptoms, particularly on the re-experiencing cluster. Phantom shock participants (n = 9) were compared with participants experiencing solely objective shocks (n = 8). Three themes emerged from our qualitative analysis: 1) Phantom shocks -- a somatic experience; 2) The emotional impact of phantom shocks; 3) Searching for meaning. Effect size analyses suggested a medium effect on symptoms of depression, PTSD, and pain anxiety, where phantom shock participants exhibited elevated levels as compared to their objective shock counterparts. Implications of these findings are discussed.