Abstract 11595: Predicting Appropriate Shocks In Patients With Heart Failure: Patient Level Meta-analysis From SCD-HeFT and Madit II

Background: Some patients implanted with a primary prevention implantable cardioverter defibrillator (ICD) due to heart failure receive an appropriate shock, but no precise tools exist to predict this outcome. Methods: Using patient level data from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), we identified patients with any appropriate ICD shock. A variety of clinical and demographic variables were included in a logistic regression model to predict appropriate ICD shocks (Table). Results: There were 1,463 patients randomized to ICD from the two included trials; 285 (19%) had ≥1 appropriate shock over a median follow up of 2.59 years. Compared with patients with no appropriate shocks, patients who received any appropriate ICD shock tended to have NYHA class II or III heart failure symptoms, beta blocker therapy, lower LVEF, wider QRS duration, and a single versus dual chamber ICD (79% of all patients had a single chamber ICD). Other comorbidities were similar between groups. Significant independent predictors of appropriate ICD shocks included NYHA class (NYHA II vs I: OR 1.65, 95% CI 1.07-2.55; NYHA III vs I: OR 1.74, 95% CI 1.10-2.76), LVEF based on one unit change (higher vs lower LVEF: OR 0.96, 95% CI 0.94-0.98), beta blocker therapy (presence vs absence: OR 0.96, 95% CI 0.94-0.98), and single chamber ICD (OR 1.67, 95% CI 1.13-2.45). Conclusion: In this meta-analysis of patient level data from MADIT-II and SCD-HeFT, appropriate ICD shocks were significantly predicted by NYHA class, LVEF, beta blocker therapy, and single chamber ICD. There is a compelling need for a large, prospective study to better define the risk of appropriate ICD shocks in patients meeting criteria for a primary prevention ICD. Until such time, stratification of patients by these factors may better define risk for potentially mortal rhythm events that might be prevented by a primary prevention ICD.