Isolated subcutaneous implantable cardioverter-defibrillator generator displacement causing inappropriate shocks despite preserved lead tip and coil position: a case report

BACKGROUND: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are increasingly used in patients without a pacing indication, and may reduce venous complications, endocarditis and extraction morbidity. Subcutaneous implantable cardioverter-defibrillator displacements may be less obvious than their transvenous counterparts. CASE SUMMARY: A 59-year-old man was found to have dilated cardiomyopathy associated with heavy alcohol intake following investigation for a stroke. Despite 2 years of alcohol cessation and optimal drug therapy, his ejection fraction remained severely impaired, and he received an S-ICD using the manufacturer recommended screening and implant method, and by an experienced operator. Ten months later, inappropriate shocks were delivered despite optimal programming. Device displacement was demonstrated by lateral chest radiography on the second instance of inappropriate therapy. On the first admission, a lateral film was not performed, and simple device programming was undertaken which failed to prevent the second occurrence. The patient requested an explant; as ventricular function had improved following initiation of sacubutril/valsartan, the clinical team opted to remove the device. DISCUSSION: Careful inspection of lateral chest films and review of device indication are needed to reduce the risk of inappropriate shocks. This is the first description of inappropriate device activity following lone generator displacement—lead displacement is well described.