21. Which intervention is appropriate for definitive therapy in a patient with atrial fibrillation with a fast ventricular response refractory to high doses of AV blocking agents and that has failed a rhythm control strategy?

A. AV node ablation

B. AV node ablation and permanent pacemaker implantation

C. Direct current cardioversion

D. Atrial fibrillation ablation (pulmonary vein isolation)

E. Both B and D are reasonable