Abstract 19480: Young African Americans with Nonischemic Cardiomyopathies and Wide QRS Intervals Are At Higher Risk of Elevated Defibrillation Threshold
Introduction: Routine defibrillator function threshold (DFT) testing for all patients undergoing implantable cardioverter defibrillator (ICD) implantation has been recently called into question. We sought to identify patients at risk for a high DFT- a group in which selective DFT testing would be warranted.
Methods: All patients who received an initial ICD implantation, ICD generator change, or device upgrade at The University of North Carolina at Chapel Hill during the past 24 months were retrospectively reviewed. Of these, 237 patients underwent DFT testing either at the time of or within 6 months of the index procedure. A high DFT was defined as a DFT test with <10J safety margin on initial testing.
Results: A high DFT was discovered in 17 (7%) of the 237 patients who underwent DFT testing. The remaining 220 patients with acceptable DFT served as the control group. The high DFT patients were predominately male, <55 years old, and African-American (see Table). Nonischemic cardiomyopathy was present in 15 (88%). Only 2 (12%) patients were on amiodarone, 4 (24%) had a right sided device, 3 (18%) had congenital heart disease, and 4 had an abnormal GFR. No patients carried the diagnosis of COPD. Primary prevention was the indication in 16 (94%). The mean age was 46.2 years old (±15.7) and the mean QRS duration was 144.8 msec (±36.5). The mean age and QRS duration in the control group were 60.8 years old (±13.7) and 119.4 msec (±30), respectively. Comparison of the two groups revealed statistically significant differences in age, race (African-American), QRS duration, and etiology of cardiomyopathy (see Table). Chi-square test and student t test were used to compare the two groups.
Conclusions: In conclusion, young patients of African-American descent, with nonischemic cardiomyopathy and a wide QRS were at increased risk of a high DFT. These characteristics, as well as the relatively high prevalence of a high DFT, reflect a population in which DFT testing should continue to be considered.
- © 2010 by American Heart Association, Inc.