Influence of patient characteristics in the selection of patients for defibrillator implantation (The AVID Registry)

The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial is a prospective, randomized study of treatment for life-threatening ventricular arrhythmias. Patients who are eligible for the main trial but who are not enrolled for any reason are followed in a registry. The objective of the present study was to determine whether there are identifiable patient characteristics among these registry patients that may influence whether a patient is treated with an implantable defibrillator. The 914 patients in the registry were divided into 2 groups according to whether the primary treatment was an implantable defibrillator. The mean age of defibrillator patients was 60 years, compared with 65 years in the nondefibrillator group (p <0.001). Only 11.2% of defibrillator recipients were minorities, whereas the percentage of minorities in the nondefibrillator group was 18.7% (p <0.003). A history of recurrent ventricular fibrillation was more likely in the group treated with defibrillators (8.9% vs 4.4%, p <0.01), whereas a history of atrial fibrillation or diabetes mellitus were both significantly more likely in the nondefibrillator group. Among defibrillator patients, a higher proportion had ventricular fibrillation as the index arrhythmia; patients with ventricular tachycardia were significantly more likely to be heated without devices. In this prospective but nonrandomized cohort of patients treated for life-threatening ventricular arrhythmias, older age, minority status, and comorbidity reduced the chances that a patient would be treated with a defibrillator.