Catheter Ablation of Atrial Fibrillation in Heart Failure

Rationale: The overall aim of the proposed research project is to identify novel aspects of the interrelationship between atrial fibrillation (AF) and congestive heart failure (CHF), two of the most common hospital discharge diagnoses, which are associated with considerable morbidity and mortality. The frequent coincidence of these two conditions is associated with a nearly two-fold increase in mortality compared to either AF or CHF alone. There are two basic treatment strategies for AF: attempting to maintain sinus rhythm or focusing on rate control of AF. Prior studies of rate versus rhythm control of AF have failed to demonstrate any definable benefit of rhythm control. This likely reflects the inefficacy of achieving effective rhythm control with antiarrhythmic drugs. Catheter ablation has been established as a highly effective therapeutic option for AF, with successful long-term maintenance of sinus rhythm. Novel Magnetic Resonance Imaging (MRI) techniques are very well suited to evaluate atrial and ventricular size and function. However, the effect of rhythm control by means of catheter ablation of AF versus rate control of AF on atrial and ventricular remodelling and function, functional capacity, neurohumoral status and morbidity remains unclear. Overall Objective: We will test the hypotheses that in patients with CHF and AF, maintenance of sinus rhythm with catheter ablation of AF as compared to rate control of AF with antiarrhythmic drugs results in reverse remodeling and improved function of both the atria and the ventricles, improvement of functional and exercise capacity, neurohumoral status, reduction of hospitalization rate and improvement of Quality of Life. Study Design: The study design is a prospective, randomized clinical trial enrolling patients with symptomatic CHF, left ventricular dysfunction, and symptomatic AF to either pharmacological rate control or to rhythm control with catheter ablation of AF. A total of 100 patients (50 patients in each treatment group) will be enrolled over a one-year period and followed for a minimum of 6 months. Novel high-resolution MRI techniques available at Johns Hopkins University will be used to perform detailed characterization of the structure and function of the atria and ventricles in the two groups. Specific Aim #1: To evaluate size and function of the right and left ventricle in CHF patients with AF randomized to effective rate versus rhythm control with MRI at baseline and at 6 months of follow-up. Specific Aim #2: To evaluate size and function of the atria in these patients with MRI at baseline and at 6 months of follow-up. Specific Aim #3: To evaluate functional (assessed by NYHA Class) and exercise capacity (6-minute walk test), neurohumoral status (BNP), morbidity (hospitalization rate), and Quality of Life (Minnesota Living with Heart Failure Questionnaire) in these patients at baseline and at 6 months of follow-up. The answers to these specific questions should contribute to a better understanding of the interrelationship between CHF and AF and should result in novel diagnostic and therapeutic strategies for these major cardiovascular health burdens.