Abstract 12223: ICD Defibrillation Threshold Testing in Patients With Hypertrophic Cardiomyopathy Should Not be Abandoned
Introduction: Defibrillation threshold testing (DFT) in patients undergoing ICD implantation has been routine, until recent data argue against such testing. In addition, a clear trend towards implantation of single coil ICD leads has been advocated because of less risk with extraction compared to dual coil leads. While these trends in patients with ischemic and non-ischemic dilated cardiomyopathy may have merit, whether they can be expanded to patients with hypertrophic cardiomyopathy is not clear.
Hypothesis: Hypertrophic cardiomyopathy patients undergoing ICD implantation should undergo DFT’s to ensure adequate defibrillation thresholds.
Methods: All patients with a diagnosis of hypertrophic cardiomyopathy who were implanted with an ICD at Tufts Medical Center were examined retrospectively from the year 2000 to 2014. Patient notes as well as medical records were examined for ICD parameters, including DFT’s and ICD system adjustments. A true DFT was defined as DFT testing until failure to defibrillate was observed. Other individuals underwent testing to ensure a minimum 10J margin between successful ICD termination of VF and ICD maximum output.
Results: Two hundred forty-six HCM patients (91 female, mean age 47 + 18yrs) were included in our analysis. Of the 221 who underwent DFT testing, 60 underwent true DFTs. Of the 246 patients, 174 were implanted with a dual coil lead and 72 were implanted with a single coil lead. The mean true DFT of pts with a single coil lead was 22.8 + 7.1j while the mean DFT of dual coil implantation was 19.7 + 6.7j (p=.22). Importantly, six of the patients tested were found to have inadequate safety margins for defibrillation. Three of these six were initially implanted with a single coil lead and had replacement with a dual coil lead to achieve satisfactory DFT values. The remaining 3 had tilt adjustment, higher energy can replacement, and removing the can from the shock vector. There were no differences in age, gender, LVEF, or septal thickness between those who failed maximal energy DFTs and those who did not.
Conclusions: In patients with HCM undergoing ICD implantation, defibrillation testing should not be abandoned. DFT should especially be performed in patients with single coil ICD leads.
- Hypertrophic cardiomyopathy
- Implantable cardioconvertor defibrillator
- Structural heart disease intervention
Author Disclosures: K.R. Kumar: None. S.N. Mandleywala: None. J. Weinstock: None. M.S. Maron: None. E.J. Rowin: None. M.S. Link: None.
- © 2014 by American Heart Association, Inc.