Association Between Age and Outcomes of Catheter Ablation Versus Medical Therapy for Atrial Fibrillation: Results from the CABANA Trial

Abstract

Background: Observational data suggest catheter ablation may be safe and effective to treat younger and older patients with atrial fibrillation (AF). No large randomized trial has examined this issue. This report describes outcomes according to age at entry in the Catheter Ablation vs Antiarrhythmic Drug Therapy for Atrial Fibrillation trial (CABANA). Methods: Patients with AF age ≥65, or <65 with ≥1 risk factor for stroke, were randomly assigned to catheter ablation versus drug therapy. The primary outcome was a composite of death, disabling stroke, serious bleeding, or cardiac arrest. Secondary outcomes included all-cause mortality, the composite of mortality or cardiovascular hospitalization, and recurrence of AF. Treatment effect estimates were adjusted for baseline covariables using proportional hazards regression models. Results: Of 2204 patients randomized in CABANA, 766 (34.8%) were age <65, 1130 (51.3%) were 65-74, and 308 (14.0%) were ≥75. Catheter ablation was associated with a 43% reduction in the primary outcome for age <65 patients (adjusted hazard ratio [aHR] 0.57, 95% confidence interval [CI] 0.30-1.09), a 21% reduction for age 65-74 (aHR 0.79; 95% CI 0.54-1.16), and an indeterminate effect for age ≥75 (aHR 1.39; 95% CI 0.75-2.58). Four year event rates for ablation versus drug therapy across age groups, respectively, were 3.2% versus 7.8%, 7.8% versus 9.6%, and 14.8% versus 9.0%. For every 10-year increase in age, the primary outcome aHR increased (i.e., less favorable to ablation) an average of 27% (interaction p value= 0.215). A similar pattern was seen with all-cause mortality: for every 10-year increase in age, the aHR increased an average of 46% (interaction p value= 0.111). AF recurrence rates were lower with ablation compared to drug therapy across age subgroups (aHR 0.47, 0.58, and 0.49, respectively). Treatment-related complications were infrequent for both arms (<3%) regardless of age. Conclusions: We found age-based variations in clinical outcomes for catheter ablation compared with drug therapy, with the largest relative and absolute benefits of catheter ablation in younger patients. No prognostic benefits for ablation were seen in the oldest patients. No differences were found by age in treatment-related complications or in the relative effectiveness of catheter ablation in preventing recurrent atrial arrhythmias.