Subcutaneous implantable cardioverter defibrillator oversensing and shock delivery due to chest compressions during CPR.

We report the case of a patient who received both appropriate and inappropriate shocks from an entirely subcutaneous implantable defibrillator (S-ICD). The inappropriate shocks were due to oversensing of chest compressions in the setting of a profound postshock bradycardia. It is important to recognize that the therapy from the S-ICD can not only be withheld, as previously described, but can also be inappropriately delivered during chest compressions.