Abstract 275: VF Characteristics and ICD Shock Success: Differences Between Ischemic and Nonischemic Heart Disease
Introduction: From animal studies we know that signal characteristics of ventricular fibrillation (VF) are affected by the presence of myocardial scarring. The impact of the underlying etiology of scar formation, ischemic or nonischemic, is unknown. Whether the origin of scar formation is correlated to shock success has not been thoroughly studied either. Therefore, our aim is to compare signal characteristics of VF and shock success in ICD-patients, with either ischemic or nonischemic heart disease.
Methods: Consecutive patients undergoing Medtronic ICD implantation between 2005 and 2011 were studied. After ICD implantation VF was induced to test the device. A first ICD shock of 15J was delivered to terminate VF. Signal analysis was performed on the first 4 seconds of the induced VF. The frequency content of the signal was determined using the Fourier Analysis. In addition, the success rate of the first ICD shock was scored.
Results: A total of 229 patients were studied of whom 149 (65%) had ischemic heart disease. The dominant, fundamental and median frequency were significantly lower in patients with ischemic heart disease (Table). Also the organization index was lower. In the ischemic heart disease group 83% (124/149) had a successful first ICD shock compared to 89% (71/80) in patients with nonischemic heart disease (p=0.26).
Conclusion: Signal characteristics of induced VF are markedly different between patients with ischemic and nonischemic heart disease. VF in ischemic heart disease is slower, less regular and less organized. Shock success was not affected by the underlying etiology, but in 10-20% of cases a first shock was not sufficient. Identification of patients with a lower shock success is subject to further study.
- Ventricular fibrillation
- Spectrum analysis
- Implantable cardioconvert defibrillator
- Electric countershock
- Ischemic heart disease
- © 2011 by American Heart Association, Inc.