The invention relates to a system and apparatus, particularly adapted for use with an automatic implantable defibrillator, for monitoring electrocardiagram (ECG) data signals to provide a continuously updated recording of the ECG data. The proposed recorder responds to the operating condition of the automatic implanted defibrillator device and places into storage, for subsequent readout by the patient's doctor, ECG data both immediately preceding the onset of a ventricular fibrillation episode and also during the subsequent defibrillation activity, when one or more high energy electrical impulses are applied to the patient's heart. Selected other data regarding operation of the implanted defibrillator and pertinent to the doctor's evaluation of the patient's condition as well as the efficacy of the defibrillator unit, are also recorded by the proposed apparatus for subsequent readout. In addition, the proposed recording apparatus operates to automatically alert the patient that ventricular fibrillation has been detected and that defibrillation is to be attempted, so that appropriate precautions may be taken. Moreover, following defibrillation, the patient is alerted in a distinctive manner that defibrillation has occurred and that a physician should be contacted, as soon as possible.