In Reply:—
I thank Drs. Oxorn, Liebowitz, and Botelho for their comments. Dr. Oxorn addresses the controversial issue of when to start anticoagulating a patient with newly diagnosed atrial fibrillation (AF). The statement that “current practice is to anticoagulate such patients if AF persists longer than 48 h” is not supported by the most recent practice American College of Cardiology/American Heart Association/European Society of Cardiology guidelines for the management of patients with atrial fibrillation. 1These guidelines clearly state that for patients with newly discovered or first episode of AF: “Whether these individuals require long-term or even short-term anticoagulation is not clear, and the decision must be individualized for each patient based on the intrinsic risk for thromboembolism.” In figure 1 of my review, 2the list of published risk factors for thromboembolism related to AF is presented, and in table 14 of the American College of Cardiology/American Heart Association/European Society of Cardiology guidelines, 1recommendations are made regarding initiation of antithrombotic therapy and which agents to use. Therapy may range from none (age < 60 yr and no heart disease) to aspirin alone (age < 60 yr with heart disease but no other risk factors, or age ≥ 60 yr with no risk factors), anticoagulation alone (age ≥ 60 yr with diabetes mellitus or coronary artery disease, age ≥ 75 yr, heart failure, left ventricular ejection fraction < 35%, thyrotoxicosis, hypertension, rheumatic heart disease with mitral stenosis, prosthetic heart valves, prior thromboembolism, and persistent atrial thrombus on transesophageal echocardiography), or their combination, depending on the patient's risk. 1The risks of anticoagulation and/or antiarrhythmic drugs must be weighed against the 0–48% of patients with acute AF who convert to sinus rhythm spontaneously. 1–3In patients with multiple risk factors for thromboembolism who are not candidates for, or do not wish to receive, systemic anticoagulation, the “fast-track” approach to conversion of AF using transesophageal echocardiography is an acceptable and frequently used approach in settings where such services are available. 1,2
Dr. Liebowitz offers anecdotal experience, whereas Dr. Botelho refers to published data on the use of amiodarone for acute conversion of acute AF. In reference 9 provided by Dr. Botelho, the author accurately stresses the importance of having a placebo-controlled arm in trials examining the conversion efficacy of antiarrhythmics on acute AF, because almost 50% may convert without treatment. 4A recent meta-analysis in nonsurgical patients showed that the efficacy of amiodarone therapy for recent-onset AF was 56% at 6–8 h and 82% at 24 h compared to 43% and 56% with placebo, respectively. 5Efficacy studies of amiodarone versus placebo for the treatment (not prophylaxis) of acute postoperative AF are sparse. Furthermore, a randomized, open-label study that compared rate control versus rhythm control (amiodarone was one of five drugs used) strategies for the management of acute AF after cardiac surgery, showed no significant difference in time to conversion to sinus rhythm between the groups or in the proportion of patients free of AF at 48 h. 6Although amiodarone is widely used and has a good overall safety record compared to other antiarrhythmic drugs, it is not without cardiovascular or noncardiac toxicity. 1,4There is controversy on whether perioperative amiodarone causes severe pulmonary toxicity after cardiothoracic surgery. 7–9Considering that intravenous amiodarone therapy for 48 h costs approximately $750 per patient 10and the lack of well-designed efficacy trials in postoperative patients, I would agree with Dr. Botelho that amiodarone may be considered after a rate-control strategy has failed 24 h after onset of AF. 1Until better outcome data are available on how to manage postoperative patients who develop AF with respect to antiarrhythmic or antithrombotic therapy, the algorithms presented in my review can serve as guidelines to the individualized management of complex patients while keeping one's own institutional practices in mind. 2
