[Anticoagulation and electrical cardioversion of chronic atrial fibrillation: proposal for an abbreviated protocol].

BACKGROUND: Several weeks of prophylactic anticoagulation are routinely prescribed before and after electrical cardioversion of atrial fibrillation. Recent studies have supported the use of transesophageal echocardiography to guide early cardioversion: patients in whom no thrombus is observed are treated with heparin followed by one month of warfarin therapy after the procedure. This kind of treatment requires hospital admission during heparin infusion, because of the need for monitoring partial thromboplastin time.

AIM OF THE STUDY: To evaluate if a short at-home treatment (three days) with warfarin is sufficient to reach a good level of anticoagulation, in order to permit safe electrical cardioversion in day-hospital for patients who show no thrombi on transesophageal echocardiography.

METHODS: One hundred twenty-four patients with atrial fibrillation, who were candidates for cardioversion, were treated with warfarin: 10 mg the first and second day, 5 mg the third day in group A patients (n = 79); 15 mg the first day, 10 mg the second and third day in group B patients (n = 45). On the fourth day, INR value was measured and if it was < 2, warfarin therapy was prolonged until patients reached a good level of anticoagulation. Transesophageal echocardiography was performed when the INR was > or = 2, and patients were cardioverted with DC shock if there were no thrombi. The patients were discharged on the same day of the procedure, and warfarin therapy was continued for 4 weeks there-after. If a thrombus was detected, patients repeated transesophageal echocardiography after 6 weeks of warfarin therapy, and were cardioverted if the thrombus disappeared. Otherwise, cardioversion was deferred and they received prolonged warfarin treatment. If there was poor visualization of the left atrial appendage, patients received conventional warfarin therapy for 3 weeks before and 4 weeks after electrical cardioversion.

RESULTS: Mean INR value after three days of warfarin treatment was 2.41 in group A patients and 3.02 in group B patients. Twenty-one patients from group A and 3 patients from group B required anticoagulant therapy for a mean of 3.3 and 5.1 days, respectively, before reaching a good level of anticoagulation (INR value > or = 2). Eight patients reverted spontaneously to sinus rhythm before transesophageal echocardiography. Eighteen thrombi (15.5%) were identified on the transesophageal echocardiography, all of which were in the left atrial appendage. In 11 cases, thrombus disappeared after 6 weeks of warfarin therapy. In 7 patients (6%), the atrial appendage was not sufficiently visualized. Electrical cardioversion was performed on 109 patients and was successful in 88 (80.7%). None of them experienced a clinical thromboembolic event.

CONCLUSIONS: In the majority of patients in atrial fibrillation, a short at-home warfarin treatment is sufficient to reach a good level of anticoagulation in order to permit safe electrical cardioversion in a day-hospital situation. Larger initial doses can achieve even better results. This treatment algorithm minimizes the anticoagulation period, hospital stay, overall duration of atrial fibrillation and the time required for the mechanical function of the left atrium to return.