Atrial fibrillation remains one of the most common, and most difficult to treat, of the cardiac arrhythmias. (Click here for a quick review of atrial fibrillation.) A major and continuing area of disagreement among doctors has been whether to treat atrial fibrillation by aggressively trying to stop the atrial fibrillation and restore a normal rhythm (i.e., rhythm control), or to treat it by allowing the patient to remain in atrial fibrillation but to control the heart rate (i.e., rate control.)
On the surface, it would seem better to try to restore a normal heart rhythm. Atrial fibrillation increases the risk of stroke, and restoring a normal rhythm (it is hoped) will reduce that risk. But such rhythm control is plagued by two problems: antiarrhythmic drugs are simply not that effective in maintaining a normal rhythm; and antiarrhythmic drugs carry the risk of serious side effects. Accordingly, proponents of rate control have pointed to the relative ineffectiveness of and the risks associated with antiarrhythmic drugs as reasons to use a rate-control strategy.
Until recently, doctors had little scientific evidence to support either approach. During the past year, however, results of randomized clinical trials have been reported that, for the first time, give doctors some real guidance in deciding whether to pursue a rhythm control or a rate control strategy for most of their patients with atrial fibrillation.
Last week, results from two of these studies - the AFFIRM trial and the RACE trial - were published in the New England Journal of Medicine. In both of these clinical trials, which were orally presented earlier this year at the American College of Cardiology Scientific Sessions, the rhythm control strategy yielded no measurable benefit over the rate control strategy.
In AFFIRM, over 4000 patients with atrial fibrillation were randomized to either rhythm control or rate control strategies, and overall mortality was the measured end point. Patients in the rhythm control group had a higher mortality than those randomized to rate control, though that higher mortality did not quite reach statistical significance. Rhythm control patients also had a higher rate of hospitalization and of adverse drug side effects.
In RACE, which randomized 522 patients, results were similar.
In summary, both these trials showed a trend toward higher mortality in patients treated with rhythm control measures. The risk of stroke and of bleeding complications (from the use of anticoagulants) was the same whether patients received aggressive attempts at rhythm control, or simply rate control. Quality of life measures also failed to show any benefit in patients treated with rhythm control measures. And finally, the need to continue use of anticoagulants remained as high in the rhythm control patients as in the rate control patients.
The bottom line on rate control vs rhythm control
While these studies do not (and cannot) resolve the issue of which approach may be the better for any given individual, it now appears reasonably conclusive that across large populations of patients, no benefit can be measured for an aggressive rhythm-control approach to treating atrial fibrillation. Rate control, which is generally much easier to achieve, appears to yield equivalent results.Keep a few things in mind: The rhythm control measures used in studies required persistent efforts at rhythm control - if one drug didn't work, investigators were encouraged to engage in a series of trials with antiarrhythmic drugs. The more drugs patients are exposed to, the higher the risk of complications. Thus, a reasonable compromise strategy might be to try one, or maybe two, antiarrhythmic drugs to maintain a normal rhythm. If a normal rhythm can be maintained easily, with few or no side effects, that's probably beneficial. If normal rhythm cannot be easily accomplished, then there appears to be nothing to gain (and perhaps something to lose) by repeated efforts.
Also, these studies focused on the use of antiarrhythmic drugs as the mainstay of the rhythm-control strategy. The rapidly developing techniques for "curing" atrial fibrillation with ablation techniques were not studied (because these techniques have not yet been perfected, and are still considered experimental.) Eliminating the need for antiarrhythmic drugs might well make a rhythm control strategy superior to rate control only. These studies, therefore, merely reflect the current state of the art. Patients with atrial fibrillation should keep in mind that medical advancements will undoubtedly present them with more - and hopefully better - options within the next few years.
