When we manage patients with atrial fibrillation, we often recommend an approach of 'rate control'. But what exactly is good rate control? When is a patient's ventricular rate well-controlled, and how should we achieve it?
Acute rate control
In the acute situation, we usually aim for a ventricular rate of 80-100 beats per minute. This is commonly achieved with a beta-blocker or a rate-limiting calcium channel blocker (such as verapamil or diltiazem). Sometimes it is necessary to use amiodarone or digoxin for acute rate control, particular when left ventricular function is significantly impaired.
If a rapid ventricular rate fails to slow with drug treatment, and if the patient has symptomatic hypotension, ischaemia/angina or heart failure, then immediate DC cardioversion may be appropriate.
Chronic rate control
In chronic AF, the target for rate control in the long term depends upon symptoms. For patients who are asymptomatic, or who have tolerable symptoms, a lenient rate control strategy (resting ventricular rate <110 bpm) is recommended.
For patients with troublesome symptoms despite lenient rate control, or if there is evidence of a tachycardiomyopathy, then a strict rate control strategy should be adopted. This means aiming for a resting heart rate <80 bpm, and <110 bpm on moderate exercise.
When strict rate control approach is taken, a 24h ambulatory ECG should be performed for safety reasons (i.e. to check that there is no evidence of excessive bradycardia/pauses). It may also be appropriate to undertake an exercise test to assess the rate response to exercise.
Chronic rate control is usually achieved with a beta-blocker, rate-limiting calcium channel blocker or digitalis.
For more information on this and other aspects of AF management, take a look at the ESC Atrial Fibrillation Guidelines 2010 (and also the subsequent Focused Update in 2012). It's also worth taking a look at this study from the NEJM: