Abstract 2429: ICD Efficacy In Patients Who Developed New Onset Atrial Fibrillation After Enrollment In The MADIT-II Trial
Introduction: In the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II), the presence of atrial fibrillation (AF) at baseline was associated with an increased risk of death, and these patients received a substantial benefit from ICD therapy. In the current study, we evaluated the risk of death and the efficacy of ICD therapy in patients who developed new-onset AF after enrollment in the MADIT-II study.
Methods/Results: Hazard ratios (HR) were determined using multivariate Cox proportional hazards method. Age ≥ 65 (HR 3.02, p < 0.01), QRS duration > 120 ms (HR 2.30, p < 0.01), and NYHA functional class ≥ 2 (HR 1.78, p = 0.03) were independent predictors of new-onset AF. In both treatment arms, there was a significant increase in the risk of death after developing new-onset AF (Post-AF) (n = 25 in conventional arm, n = 51 in ICD arm) than among patients before or without AF (Pre-AF) (n = 416 in conventional arm, n = 624 in ICD arm) as shown in the Mantel-Byar graphs. After adjusting for relevant covariates (including age, BUN, EF, and beta-blocker use), ICD therapy was associated with a greater reduction in the risk of death in patients who developed new-onset AF (HR 0.31, p = 0.013) compared to patients with no interim AF (HR 0.73, p = 0.055) [p = 0.085 for interaction between interim AF and ICD therapy].
Conclusions: The development of new-onset AF is associated with a significant increase in mortality and this group may be a target for closer follow-up and more aggressive treatment. ICD therapy was highly effective in reducing mortality in MADIT-II patients who developed new-onset AF after enrollment in the trial.