AFFIRM and RACE trials: implications for the management of atrial fibrillation.

The Atrial Fibrillation (AF) Follow-up Investigation of Rhythm Management (AFFIRM) and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation Study (RACE) Trials evaluated strategies of rate control or rhythm control in atrial fibrillation. AFFIRM enrolled patients with recent onset AF, and at entry over half of all patients were in sinus rhythm. At any point in the trial, the achieved difference in cardiac rhythm was likely only about 30%. In RACE all patients were entered in AF, and at the end of the study, sinus rhythm was present in 10% vs 39%. The strategy of rate control was non-inferior to the rhythm control strategy in both trials, and permits consideration of rate control as primary therapy. However, the actual differences in rhythm were relatively small, and do not allow the conclusion that maintenance of sinus rhythm is inferior to non-maintenance. Current guidelines recommend that patients with paroxysmal AF receive warfarin if they have risk factors for stroke. This is supported by data from AFFIRM. Most strokes in AFFIRM occurred either during subtherapeutic INR, or after cessation of warfarin. Since more patients in the rhythm control arm of AFFIRM discontinued warfarin, it is possible that asymptomatic recurrences of paroxysmal AF fostered clot development and embolization. We cannot answer from the data available whether or not it is safe to discontinue anticoagulation if all episodes of AF are suppressed. Among the reasons that AF is associated with increased mortality may be that it encourages development of congestive heart failure or progressive left ventricular dysfunction. Congestive heart failure occurrence was monitored in both trials, and occurred at a rate of 2-5% without significant differences between rate and rhythm arms. In patients with heart failure at entry, a mortality trend in AFFIRM favored the rhythm control arm. The issue of survivorship and rhythm control in AF in congestive heart failure is undergoing further testing.