Dr. Wiesel argues that all patients with nonvalvular atrial fibrillation should receive long-term anticoagulation after successful cardioversion. He cites the frequent association of paroxysmal or chronic atrial fibrillation with acute stroke (1). He also raises concern that our estimate of early stroke risk (a 6-week fraction of the annualized risk) if relapse occurs is too low, given the potential for paroxysmal episodes. He refers to the study by Lin and colleagues (1), which examined the frequency of newly diagnosed atrial fibrillation in patients presenting with acute stroke. This study did not assess the occurrence of stroke in patients with previously detected atrial fibrillation or those with previous cardioversion. Thus, it does not address whether most patients restored to sinus rhythm, with or without prophylactic antiarrhythmic therapy, require warfarin beyond the first month after cardioversion. Furthermore, recent guidelines do not advocate long-term warfarin therapy after successful pharmacologic or electrical cardioversion unless the arrhythmia recurs or high-risk variables (that is, previous ischemic stroke and left ventricular systolic dysfunction) are present (2).

There is considerable debate about the optimal antithrombotic strategy for patients with nonvalvular atrial fibrillation who are restored to sinus rhythm. We agree that patients with paroxysmal atrial fibrillation, particularly if they do not sense the arrhythmia, may require longer-duration anticoagulation or more intense surveillance than suggested in our treatment paradigm. It is important to emphasize that the hypothetical cohort in our Markov model excluded patients with paroxysmal atrial fibrillation and those with previous ischemic stroke. The AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial (3) may ultimately provide definitive answers to the concerns raised by Dr. Wiesel and others (4). Until AFFIRM results are available, however, physicians need to individualize management of this common clinical condition.