Objective. The purpose of this study was to use the electrogram storage capabilities of the implantable cardioverter-defibrillator (ICD) to categorize any arrhythmic event during follow-up in a group of patients who had survived an episode of ventricular fibrillation (VF) and to possibly identify clinical predictors of future arrhythmic events. Background. Little is known about the electrophysiologic characteristics of ventricular arrhythmias recurring during follow-up in survivors of VF as the sole documented arrhythmia at the time of resuscitation. Methods. Forty patients (58 ± 10 years; 73% men; left ventricular ejection fraction 42 ± 18%; 70% with coronary artery disease) who had survived an episode of VF and subsequently received an ICD capable of intracardiac electrogram recording and storage were followed for 23 ± 11 months. In all patients, the arrhythmogenic substrate was investigated by means of programmed electrical stimulation (PES). Results. Among the 40 patients, 41 episodes of ventricular arrhythmias were documented in 13 patients (33%): 36 episodes of ventricular tachycardias (VT) were recorded in 11 patients (28%) and 5 episodes of VF were recorded in the remaining 2 patients (5%). Age, gender, cardiac disease and left ventricular ejection fraction failed to distinguish between patients with clinical recurrences and patients without. The sensitivity, specificity and positive accuracy of PES were 29%, 63% and 46%, respectively, for prediction of ventricular arrhythmia recurrence; 45%, 70% and 36%, respectively, for prediction of VT; and 50%, 98% and 50%, respectively, for prediction of VF during follow-up. Conclusions. In survivors of Vie receiving ICD therapy, VT is the most common ventricular arrhythmia recorded on device- incorporated electrograms during follow-up. This finding, associated with the relatively well-preserved ventricular function, may account for the ability of these patients to survive at time of the index arrhythmia; the use of antitachycardia pacing as a modality to treat arrhythmia recurrences may contribute to reduce the incidence of shock during follow-up in these patients.
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