Assessment of Cardioversion Using Transesophageal Echocardiography - ACUTE II


The goal of the trial was to evaluate treatment with enoxaparin compared with unfractionated heparin (UFH) among patients with atrial fibrillation (AF) undergoing transesophageal echocardiography (TEE)-guided cardioversion (CV).

Study Design

Study Design:

Patients Enrolled: 155
Mean Follow Up: 5 weeks
Mean Patient Age: Mean age 64 years
Female: 26

Patient Populations:

Persistent or paroxysmal AF >2 days in duration with the option of early electrical or chemical CV; or atrial flutter having a documented history of AF


Use of warfarin during the previous 14 days or >24 hours of UFH before study enrollment; contraindications to warfarin, heparin, or TEE; history of thrombocytopenia, bleeding, stroke <3 months, renal insufficiency, malignancy, uncontrolled hypertension, hemodynamic instability, weight <40 or >125 kg, life expectancy <6 months, history of drug or alcohol abuse within 2 years, or need for concomitant therapy known to affect platelet function or anticoagulation

Drug/Procedures Used:

Patients were randomized to the TEE-guided approach with enoxaparin (1 mg/kg subcutaneous every 12 hours; n = 76) or UFH (weight based; n = 79). Warfarin was also started at the time of randomization.

Principal Findings:

The majority of patients had AF at baseline (94%), with the median duration of AF 5 days in the enoxaparin group and 10 days in the UFH group (p = 0.11). Antiarrhythmic therapy was used in 84% of patients. Mean left ventricular ejection fraction at baseline was 47%. Mean enoxaparin dose was 88.7 mg. Duration of therapy averaged 6 days in the enoxaparin group and 5.36 days in the UFH group. TEE with CV was successful in 59/72 (82%) patients in the enoxaparin group undergoing TEE and 54/66 (82%) patients in the UFH group undergoing TEE.

There were no major bleeds in the trial; minor bleeding occurred in 4% of each group. There was no difference in the need for repeat CV (3.9% for enoxaparin vs. 7.6% for UFH, p = 0.495). Normal sinus rhythm at 5 weeks occurred more frequently in the enoxaparin group than the UFH group (76% vs. 57%, p = 0.013). Median duration from hospital admission to discharge was shorter in the enoxaparin group (4 vs. 5 days, p = 0.003). Use of antiarrhythmic therapy at 5 weeks was similar between the groups (94% for enoxaparin vs. 92% for UFH, p = 0.615).


Among patients with AF undergoing TEE-guided CV, use of enoxaparin was associated with an increase in normal sinus rhythm at 5 weeks compared with UFH without an increase in bleeding, although the overall bleeding rate was very low in the trial.

Electrical cardioversion is associated with an increased risk of stroke, which led to a combination approach of TEE with short-term anticoagulation using UFH in the ACUTE I trial. The present study sought to expand the anticoagulation options with TEE to include enoxaparin in addition to UFH. There was no adverse safety risk observed with enoxaparin over UFH in the present study, but it should be noted that the trial was small and the bleeding rate was low in both groups. The recent ACE trial showed enoxaparin was noninferior compared with UFH for the endpoint of stroke, death, or major bleeding among patients undergoing CV of AF.


Klein AL, Jasper SE, Katz WE, et al. The use of enoxaparin compared with unfractionated heparin for short-term antithrombotic therapy in atrial fibrillation patients undergoing transoesophageal echocardiography-guided cardioversion: Assessment of Cardioversion Using Transoesophageal Echocardiography (ACUTE) II randomized multicentre study. Eur Heart J 2006;27:2858-65.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Noninvasive Imaging, EP Basic Science, Atrial Fibrillation/Supraventricular Arrhythmias, Echocardiography/Ultrasound

Keywords: Stroke, Enoxaparin, Warfarin, Electric Countershock, Heparin, Stroke Volume, Hemorrhage, Echocardiography, Transesophageal, Atrial Flutter

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