D. Permanent Atrial Fibrillation
Atrial fibrillation that cannot be terminated by cardiover-sion, that can be terminated only for brief intervals, or that lasts longer than one year without cardioversion having been attempted is classified as permanent. Chronic atrial fibrillation implies continuing atrial fibrillation and does not address the important clinical distinction between persistent and permanent atrial fibrillation.
In the vast majority of patients with permanent atrial fibrillation, slowing of the ventricular response to 70–90 beats per minute will be helpful. A beta-blocking drug such as metoprolol, bisoprolol, or atenolol should slow down the ventricular response. These agents are also a good choice in patients with concomitant congestive heart failure New York heart Association class I–III. Digoxin was commonly used for this condition from the 1950s to 1990, but during the past decade beta-blockers have become the agents of choice, mainly because it became apparent that digoxin does not achieve the control of a fast ventricular rate associated with exercise. In patients in whom beta-blockers cannot be used safely, the ventricular rate can be slowed sufficiently with the inexpensive digoxin administered once daily. Occasionally a combination of a beta-blocker and digoxin becomes necessary.

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