Predictors of long-term mortality in Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) patients with implantable cardioverter-defibrillators

BackgroundData on long-term follow-up and factors influencing mortality in implantable cardioverter-defibrillator (ICD) recipients are limited.ObjectiveThe aim of this study was to evaluate mortality during long-term follow-up and the predictive value of several risk markers in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) patients with implanted cardioverter-defibrillators (ICDs).MethodsThe study involved U.S. patients from the MADIT II trial randomized to and receiving ICD treatment. Data regarding long-term mortality were retrieved from the National Death Registry. Several clinical, biochemical, and electrocardiogram variables were tested in a multivariate Cox model for predicting long-term mortality, and a score identifying high-, medium-, and lower risk patients was developed.ResultsThe study population consisted of 655 patients, mean age 64 ± 10 years. During a follow-up of up to 9 years, averaging 63 months, 294 deaths occurred. The 6-year cumulative probability of death was 40%, with evidence of a constant risk of about 8.5% per year among survivors. Median survival was estimated at 8 years. Multivariate analysis identified age >65 years, New York Heart Association class 3–4, diabetes, non–sinus rhythm, and increased levels of blood urea nitrogen as independent risk predictors of mortality. Patients with three or more of these risk factors were characterized by a 6-year mortality rate of 68%, compared with 43% in those with one to two risk factors and 19% in patients with no risk factors.ConclusionA combination of a few readily available clinical variables indicating advanced disease and comorbid conditions identifies ICD patients at high risk of mortality during long-term follow-up.