A validated risk model for 1-year mortality after primary prevention implantable cardioverter defibrillator placement

Objective We sought to determine survival for patients with heart failure after an implantation of an implantable cardioverter defibrillator (ICD) for primary prevention in the United States and to develop a simple model that would predict mortality risk. Background Clinical trials have found that patients with heart failure with a 1-year mortality risk near 20% may not benefit from an ICD. Methods We identified patients from the ICD Registry of the National Cardiovascular Disease Registries who underwent ICD implantation for primary prevention from 2007 to 2009. Two risk scores for mortality were developed in 2 cohorts: one limited to those with a B-type natriuretic peptide (BNP) value and a second for all patients. The scores were obtained from derivation datasets and tested in a validation sets using logistic regression models and classification and regression trees. Results In a primary prevention population with BNP available (18,725) the 6 variables most predictive of 1-year mortality were age >= 75, BNP >= 700 pg/mL, chronic lung disease, dialysis, blood urea nitrogen >= 30 mg/dL, and systolic blood pressure <120 mmHg. Patients with zero risk factors had a 3.3% one-year mortality compared to a 66.7% one-year mortality for those with all 6 risk factors. Those with >= 3 risk factors (24.0% of the population) had a 25.8% one-year mortality. A second score using a larger cohort that did not consider BNP identified similar risk factors. Conclusions A simple validated risk score can identify patients at high and low risk for death within a year after ICD placement. A large fraction of those currently implanted with an ICD in the United States have a high 1-year mortality and may not benefit from ICD therapy.