Abstract 3085: Predictors of Shocks in the First Year After an Implantable Cardioverter Defibrillator (ICD)
Determining who will receive a shock after an implantable cardioverter defibrillator (ICD) is a significant clinical problem because receiving an ICD shock has been linked to anxiety, depression, and the development of PTSD. If risk factors for ICD shocks can be identified, then preventive strategies could be implemented in this group.
The purpose of this study was to predict ICD shocks using demographic and clinical characteristics in the first year post-ICD.
Methods: A prospective design was used to follow 168 first time ICD recipients over 12 months. Demographic data were obtained from medical records at the time of ICD insertion. ICD shock data were obtained from ICD interrogation reports at hospital discharge, 1, 3, 6, and 12 months.
Results: All subjects received an ICD for secondary prevention of cardiac arrest, were 64.1 ± 12.4 years old, 89% Caucasian, 77% male, with a mean ejection fraction (EF)%= 33.7% ± 14.1. The cumulative % of ever receiving an ICD shock over 12 months was 33.3%, with 1% receiving an ICD shock during hospitalization, 12.6% by 1 month, 7.5% at 3 months, 7.1% at 6 months, and 17.3% at 12 months. Using logistic regression, the following variables were analyzed for their prediction of ICD shocks: age, gender, anxiety, EF, depression, diabetes, hypertension, smoking, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), ICD implantation reasons, history of ventricular fibrillation (VF), using beta blocker medications, and body mass index (BMI). Of these, three variables predicted shocks in the first year after an ICD: history of COPD (OR 4.42, 95% CI 1.2–16.4, p=0.03), history of CHF (OR 3.55, 95% CI 1.4–9.3, p=0.0l), or unmonitored syncope with ventricular tachycardia (VT) at the time of ICD implantation (OR 10.05, 95% CI 1.8 -55.6, p=0.0l). Model statistics suggested that the model fit the data well (X2 = 33.43, p = 0.05).
Conclusions: The presence of COPD, CHF, or VT at ICD implant were significant predictors of ICD shocks in the first year post-ICD. Risk factors associated with receiving an ICD shock will assist clinicians in reducing the incidence of ICD shocks for patients. Preventing ICD shocks will perhaps significantly reduce psychological distress and the development of PTSD.