Abstract 17395: Injury Current After Spontaneous Ventricular Arrhythmia With or Without ICD Therapy is Associated With Higher Risk of Both Sudden Arrhythmic and Pump Failure Death
Introduction: Appropriate and inappropriate ICD shocks are associated with increased risk of death. However, mechanisms of increased mortality are not completely understood. We hypothesized that local injury current after ICD-treated ventricular tachyarrhythmia (VT) is associated with increased risk of both sudden arrhythmic and pump failure death.
Methods: Near field (NF) bipolar right ventricular (RV) electrograms (EGMs) recorded immediately before the onset of arrhythmia and 10 sec after ICD therapies (both shock and antitachycardia-pacing [ATP]) that were extracted from ICD or CRT-D device memory and resting NF RV EGM were recorded and analyzed by custom Matlab software. Data from 672 patients (mean age 60.8±14.8, 484 [73%] male) with structural heart disease and ICD or CRT-D implanted for primary (561 patients, 83%) or secondary prevention of SCD were analyzed. Local injury current (LIC) on the NF RV EGM was defined as a deviation of EGM potential ≥1 mV or ≥15% of the preceding R wave peak-to-peak amplitude. Patients were followed prospectively at least 6 months after ICD therapy.
Results: Overall 426 events with stored digital EGMs were analyzed. Negative injury current was more prominent after appropriate or inappropriate ICD shock, compared to ATP — terminated VT (−1.7±1.98 vs. 0.03±0.72 mV; P<0.0001). LIC was observed in 77 out of 124 appropriate ICD shocks (50%), in 22 out of 37 inappropriate ICD shocks (60%), in 27 out of 138 appropriate ATP (20%), in 3 out of 16 inappropriate ATP (19%), and in 20 out of 86 non-sustained (NS) VT (23%). In 18±6 months of follow-up 39 patients sustained fast VT or SCD, and 64 patients died due to pump failure. LIC after any ICD therapy or NSVT was associated with 5 fold increased risk of SCD or PVT/VF in multivariate Cox regression analysis (HR 5.06, 95% CI 2.59–9.80; P<0.0001), with a model including the use of amiodarone and NYHA class. The risk of subsequent pump failure death or hospitalization due to heart failure exacerbation was twice higher among LIC patients (HR 2.46, 95%CI 1.35–4.50; P=0.003).
Conclusion: Injury current after any ICD therapy or without it is associated with higher risk of both sudden arrhythmic and pump failure death. The mechanisms that underlie the local injury current phenomenon deserve further study.
- Ventricular arrhythmia
- Heart failure
- Sudden cardiac death
- Implantable cardioconvert defibrillator
- Resynchronization therapy
- © 2010 by American Heart Association, Inc.