Abstract 11492: Ventricular Tachyarrhythmia Recurrence in Implantable Cardioverter-Defibrillators (ICD) Implanted for Primary versus Secondary Prevention and Role of Electrophysiologic Study (EPS)
Introduction: In recent years there has been a shift away from performing EPS to guide ICD implantation. This study compares ICD activations in primary prevention ICD patients with left ventricular ejection fraction (LVEF)≤40% and inducible ventricular tachycardia (VT) at EPS (Group 1, n=130), primary prevention ICDs based on LVEF≤35% alone (Group 2, n=237) and secondary prevention ICDs (Group 3, n=211).
Methods: We recruited patients from the COMFORT trial, a multi-centre prospective study assessing effectiveness of anti-tachycardia pacing for very fast VT in ICD patients. Follow up was at 1, 3, 6, and 12 months, then 6 monthly thereafter. All ICD activations and deaths were analysed by an independent committee.
Results: A total of 578 patients, mean age 65±12, were prospectively recruited from 6 centers across Australia from May 2008 to May 2010. Mean LVEF was higher in Group 3 (p=0.01). After a median follow up of 19±9 months 38% of Group 3 experienced an appropriate ICD activation versus 21% of overall Groups 1 and 2 (p<0.01). A higher proportion of appropriate ICD activations occurred in Group 1 compared to Group 2 (27% vs 16%, p=0.02). There was no statistical difference between groups for inappropriate ICD activations (p=0.28), median time from enrolment to first appropriate ICD activation (p=0.79) and cycle length of first appropriate arrhythmia (p=0.54). The estimated 2 year arrhythmia-free survival was 76.5±0.1%, 79.8±0.1% and 70.6±0.1% in Groups 1, 2 and 3 respectively (log rank p=0.01).
Conclusions: Primary prevention ICD patients with inducible VT experienced more arrhythmic events than those based on LVEF alone. Secondary prevention patients experienced a higher number of appropriate ICD activations, compared to primary prevention patients with a lower overall arrhythmia free survival.
- © 2011 by American Heart Association, Inc.