Among patients with AF treated with beta-blockers, the heart rate (HR) response varies substantially. Sometimes, adequate rate control can be achieved by titration of the beta-blocker dose; but frequently, additional AV nodal blockers and/or digoxin are necessary. In some cases, adequate rate control cannot be achieved even with the simultaneous use of multiple AV nodal blockers, necessitating mechanical ablation of the AV node and permanent pacemaker implantation.