I beg to differ with the above opinion. An AICD is designed to deliver a shock whenever the patient's heart rate falls outside of the programmed limits. (They do basically the same job as the defibrillators used for a cardiac arrest). Unless there truly is a malfunction in the unit you should code the reason the patient received the shock, ie. tachycardia, SVT, A-Fib, bradycardia or whatever. If a patient receives a shock from the AICD the device is then interrogated to discover the reason. Careful review of the medical record, or a query to the provider should give you your answer. You should only code 996.04 if the AICD is actually malfunctioning and this too should be clearly stated in the medical record.