Rate control in stable persistent atrial fibrillation
For most stable adults with persistent atrial fibrillation (AF, atria quivering chaotically; persistent means continuous for more than a week), the first-line strategy is rate control: drugs slow the ventricles.
Remember
For most stable adults with persistent AF, start rate control, usually with a standard beta-blocker such as bisoprolol. Rhythm control (resetting the rhythm) is considered if symptoms continue after the rate is controlled or rate control has not worked, and digoxin on its own is reserved for people who do very little exercise or cannot take the other drugs.
In atrial fibrillation (AF), the atria (the upper chambers) quiver chaotically. The AV node, the gateway between the atria and ventricles, then passes an irregular and often fast stream of impulses on to the ventricles. AF is called persistent when it is continuous for more than a week.
A person who is haemodynamically stable has blood pressure and circulation holding up. For most such people, NICE says to offer rate control as the first-line strategy. That means using drugs to slow the ventricular rate while the AF continues. Exceptions include a reversible cause, new-onset AF and AF thought to cause heart failure.
NICE usually offers either a standard beta-blocker (any beta-blocker other than sotalol, for example bisoprolol) or a rate-limiting calcium channel blocker (slowing the ventricular rate: diltiazem or verapamil) as the first drug. It is chosen according to symptoms, heart rate, other conditions and preferences. Beta-blockers block the effect of adrenaline on the AV node, so it passes fewer impulses on and the ventricular rate falls.
If the person has heart failure with reduced ejection fraction (a weak pump that ejects too small a share of the blood in the left ventricle with each beat), that settles the choice of first drug. Beta-blockers such as bisoprolol are part of the recommended treatment for this type of heart failure, whereas verapamil and diltiazem should be avoided because they weaken the force of each contraction.
NICE reserves digoxin monotherapy (one drug on its own) for people with non-paroxysmal AF who do very little exercise or for whom other rate-limiting drugs are ruled out. Paroxysmal AF comes in episodes that stop by themselves; non-paroxysmal AF is continuous. Rhythm control, which resets the rhythm, is considered when symptoms continue after the rate has been controlled or rate control has not been successful.
Key facts
- Strategy
- rate control is first-line for most people with AF, and it slows the ventricles without trying to restore a normal rhythm.
- Persistent AF
- AF that is continuous for more than a week.
- First drugs
- a standard beta-blocker (not sotalol), or a rate-limiting calcium-channel blocker (diltiazem or verapamil).
- Heart failure with reduced ejection fraction
- use a beta-blocker and avoid verapamil and diltiazem.
- Digoxin
- NICE reserves digoxin monotherapy for people with non-paroxysmal AF who do very little exercise or for whom other rate-limiting drugs are ruled out.
- Stroke prevention
- whether to give anticoagulation (to reduce stroke risk) is a separate decision, based on stroke risk (CHA2DS2-VASc score), not on the rate-control drug.
- Emergency
- emergency electrical cardioversion (a controlled shock that resets the heart rhythm) is for life-threatening haemodynamic instability caused by new-onset AF.
Exam traps
- Immediate cardioversion is not the first step for a stable person, because emergency electrical cardioversion is for life-threatening haemodynamic instability.
- Digoxin does control the ventricular rate, but NICE reserves digoxin monotherapy for non-paroxysmal AF in people who do very little exercise, or when other rate-limiting drugs are ruled out, so an active person with no reason to avoid a beta-blocker should not start with it.
- Verapamil is a listed rate-control option, but NICE says to avoid it in heart failure with reduced ejection fraction, because it weakens the force of the heart's contraction (negative inotropy).
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