Abstract 11318: Effect of Cardiac Resynchronization Therapy on Defibrillation Threshold Estimates
Introduction: Defibrillation thresholds (DFTs) are typically stable over time among patients (pts) with implantable cardioverter defibrillators (ICD). However, the impact of cardiac resynchronization therapy (CRT) on DFTs has not been well studied. Accordingly, the present trial was a prospective evaluation of the effect of CRT and reverse remodeling on DFTs.
Methods: This prospective, multicenter study evaluated 55 CRT-D pts. Echocardiography and DFTs were performed both at implant and 6-months post implant. All pts were implanted with a dual coil lead and DFTs were measured using a binary search method and tuned waveforms where the shock pulse width determined by shock impedance. Echocardiograms were analyzed by an independent core lab with a responder defined as a decrease of left ventricular end systolic volume (LVESV) > 15%.
Results: The study cohort was 65% male with a mean age of 69.1 ± 14.4 years. The baseline EF was 27.6 ± 7.8% and NYHA class per specific activity scale was 2.9 ± 0.4. There was no significant change in DFT peak voltage, delivered energy (Joules) or shock impedace over time (Table 1). Similarly, reverse remodeling did not impact DFT at 6 months. In CRT responders (n = 32) the mean DFT was 415.6 ± 108.1 V at implant vs. 415.6 ± 124.7 V at 6-month (p = 0.9) and in non-responders (n = 19) the mean DFT was 452.6 ± 102 V at implant vs. 447.4 ± 112.4 V at 6-month (p = 0.8).
Conclusions: DFTs were stable at 6 months in CRT patients with or without reverse remodeling.
- © 2010 by American Heart Association, Inc.