2 randomized clinical trials

AFFIRM Trial (Wyse et al, NEJM 2002 Dec 5; 347:1825)
RACE Trial (VanGelder et al, NEJM 2002 Dec 5; 347:1834)
Both showed no benefit to patients with atrial fibrillation assigned to rhythm control (using antiarrhythmic
drugs) when compared to patients assigned to rate control. Indeed, in both trials there was a tendency
toward better clinical outcomes in the rate control groups; this latter finding is generally interpreted as yet
more evidence of the toxicity of antiarrhythmic drugs. Furthermore, systemic embolization was not reduced
in the rhythm control group, so once a patient has had a chronic or persistent atrial fibrillation, chronic
anticoagulation apparently remains necessary, even if sinus rhythm is successfully restored and
maintained.  
The bottom line: for now, in general, rate control is the generally accepted standard of
treatment for patients with chronic or persistent AF.

AFFIRM and RACE do not, however, tell the whole story. Consider the following:
-Some patients are significantly symptomatic when they are in atrial fibrillation, even if their heart rates are
controlled. Usually these patients have stiff non-compliant ventricles (
diastolic dysfunction). Such
patients rely heavily on effective atrial contractions, which allow them to maintain the high left ventricular
end-diastolic pressures they require while at the same time maintaining relatively normal mean left atrial
pressures. With the onset of atrial fibrillation , the only way to
maintain these high LVEDPs is to
immediately and dramatically increase the LAP, leading to symptoms related to pulmonary congestion. In
individuals like this, no matter what the randomized trials may say, maintaining sinus rhythm is imperative.

-
Patients with normal hearts and occasional episodes of AF almost always feel much better in NSR.
Maintaining SR in these patients is often the more favorable approach. These patients were
underrepresented in both the AFFIRM and RACE trials.

-A published sub-study from the AFFIRM trial suggests that patients who actually achieved chronic sinus
rhythm (as opposed to patients merely randomized to rhythm control) had improved clinical outcomes
(Corley et al, Circulation 2004; 109:1509)

-A non-randomized study (Hsu et al, NEM 2004; 351:2373) suggests that in patients with chronic
congestive heart failure and rate-controlled AF, the successful ablation of AF yields a significantly
improved QOL.

-These considerations emphasize once again that rate control is the standard of therapy not because it is
a perfectly adequate treatment, but because the alternatives are so unappealing. The lack of benefit from
rhythm control seen in randomized studies seems most likely an artifact of our currently ineffective and
risky methods for maintaining sinus rhythm.
AF
2014 ACC/AHA AF Guidelines
2006 ACC/AHA AF Guidelines
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