A comparison of long-standing implantable cardioverter-defibrillator patients with and without appropriate therapy for ventricular arrhythmias: impact of a widening QRS

AIMS: The comparison of patients with long-standing implantable cardioverter-defibrillators (ICDs) who have had or never have had appropriate therapy for ventricular arrhythmias may offer insight into potential risk factors that may improve patient selection. METHODS AND RESULTS: Records from patients in the Columbia Presbyterian device clinic whose original ICD was implanted before 31 December 2004 were analysed. The patients were divided into those who had never received appropriate therapy for ventricular arrhythmias (Group A, n = 188), and those who had received appropriate therapy (Group B, n = 173). The subset of patients with consistent follow-up greater than 5 years was then analysed (Group A, n = 140; Group B, n = 158). Demographic, clinical, echocardiographic, and electrocardiographic data were collected. There were no significant differences in age, sex, or type of heart disease between the groups. There were more patients in Group B vs. A who had ICDs implanted for secondary prevention (70.3 vs. 55.7%, P < 0.05). The mean QRS width was similar at implant but increased significantly in Group B vs. A on pre-ICD discharge electrocardiograms (134.1 ± 35.0 vs. 125.1 ± 36.2 ms, P < 0.05). Congestive heart failure class, comorbidities, use of antiarrhythmic agents, or left ventricular ejection fraction were not discriminators between Groups A and B. CONCLUSION: In this study of patients with long-standing ICDs, the only discriminating factors for appropriate shocks were implant for secondary prevention or increasing QRS width, suggesting electrical factors are the best predictors of ultimate ICD discharges.