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Atrial fibrillation can either be managed with rate control or rhythm control. Rate control allows the patient to remain in atrial fibrillation but controls the heart rate by slowing conduction at the AV node with various medications. The heart rate is considered to be controlled when it is between 60-80 beats per minute at rest and between 90-115 beats per minute during moderate exercise. Rhythm control allows for cardioversion back to normal rhythm either with medications or electrical shocks.

In the past, many cardiologists assumed that patients with persistent atrial fibrillation would benefit most from aggressive treatment to maintain normal sinus rhythm (i.e., rhythm control). A major study published in 2002, called the Atrial Fibrillation Follow-Up Investigation of Rhythm Control (AFFIRM), randomized patients with atrial fibrillation to either rate control or rhythm control groups and, surprisingly, found no major differences among the two groups with respect to death rates or overall morbidity. Most surprisingly, the rate of ischemic stroke for the patients in the rhythm control arm of the study was not lower (as had been expected) than for the patients in the rate control group. Based on these findings, the investigators concluded that rate control, in conjunction with anticoagulation, was equally effective as rhythm control in preventing morbidity and mortality in patients with atrial fibrillation. The major findings of the AFFIRM study have since been confirmed by other clinical trials such as the Rate Control versus Electrical Cardioversion (RACE) study.

The AFFIRM and RACE studies showed that rate control and rhythm control, eacj with chronic anticoagulation, are both acceptable approaches in patients with atrial fibrillation. The choice of strategy does depend on specific factors such as whether or not it is the patient's first episode, the presence of hemodynamic instability, and whether or not the patient has symptoms. If a patient has a first episode of atrial fibrillation and is bothered by symptoms such as palpitations or shortness of breath it is acceptable to try a strategy of rhythm control. However, if the patient does not easily convert to sinus rhythm or does not stay in sinus rhythm for a long period of time, it is acceptable to just control the patient's heart rate (rate control) since the long term chance of survival is similar with both strategies.

For additional information about the AFFIRM study, the reader is referred to the following article:

• A comparison of rate control and rhythm control in patients with atrial fibrillation. New England Journal of Medicine 2002, December 5; 347(23):1825-33.

Abstract Link:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12466506

Regardless of which treatment options are chosen for long term therapy, it will be necessary to give medications to slow the heart rate. If the patient is hypotensive (low blood pressure) or shows signs of congestive heart failure, direct current (DC) cardioversion should be done promptly. If the situation is not urgent, the heart rate can be controlled with medications such as digoxin, a beta blocker, or a calcium channel blocker. For patients with decreased heart function, digoxin and beta blockers are useful while calcium channel blockers are contraindicated. For patients with asthma or other contraindications to beta blockers, the calcium blockers may be useful as long as heart function is normal or near normal.