Abstract 9039: Predictors of High Defibrillation Energy Requirements: Results From the NCDR ICD Registry

Abstract

Background: Defibrillation testing is typically performed at the time of ICD implantation to establish effective arrhythmia termination. Despite technological advancements, including biphasic waveforms and higher output devices, an inadequate safety margin for defibrillation may still occur. The NCDR ICD Registry was examined to evaluate predictors of a high defibrillation requirement (DER) using modern day devices. Methods: Patients who underwent defibrillation testing in the NCDR ICD Registry were examined to determine characteristics associated with a high DER. This included 45,686 initial ICD implantation procedures from April 2010 to December 2010 performed at 1261 facilities. Patient characteristics were compared using chi-square tests for categorical variables and unbalanced t-tests for continuous variables. Multivariable logistic regression was used to assess independent predictors of a "high" DER, which was defined as >25 joules. Results: A high DER was noted in 4.1% of patients undergoing testing. Patients with a high DER were more often younger, male, on dialysis, and were more likely to have a higher NYHA functional class, lower LVEF, higher creatinine, and wider QRS. Patients on antiarrhythmic drugs and those with nonischemic heart disease were more likely to have a high DER. Independent predictors of a high DER included younger age, higher NYHA class, and increased QRS duration. A high DER was associated with longer post-procedure length of stay (1.6 ± 2.9 vs. 2.1 ± 3.8 days, p<0.001) as well as any complication or death prior to hospital discharge (2.6% vs. 4.0%, p<0.001). Conclusions: A high DER was observed in 4.1% of patients and was associated with more complications and mortality. Several clinical predictors of a high DER were identified, potentially enabling the identification of patients most likely to benefit from testing. Additional study is needed to determine if testing predicts long-term outcome of patients with modern day devices.