At least three weeks of oral anticoagulation (OA) is usually recommended for the prevention of thromboembolic events after external cardioversion (EC) in patients with atrial fibrillation (AF). In the past years, along with the use of transesophageal echocardiography (TEE), short-term heparin utilization has been shown to reduce the risk of thromboembolism. Recently, several studies on the use of transcranial Doppler (TCD) have elucidated absence of microemboli formation after EC in patients undergoing 3 weeks of OA before procedure. At the same time it is not yet known whether there is a risk of microemboli after short-term heparin infusion and EC. We aimed to compare the risks of microemboli formation after EC using TCD in patients with AF undergoing long-term oral anticoagulation and short-term heparinization before the procedure.
METHODS Forty-three patients scheduled for elective EC due to chronic AF, without signs of intracardiac thrombi on TEE and with sufficient temporal window for transcranial Doppler (among them 21 women, mean age 62±13), were included into the study. While nineteen of the patients received effective OA with INR between 2-3 due to AF (Group 1), 24 patients were heparinized (aPTT=70-80ms) before EC (Group 2). Transcranial Doppler sonography of right and left cerebral arteries, accomplished using two channels 2 MHz probe through temporal bone approach, was performed 30 minutes before and 30 minutes after the EC for the detection of microemboli.
RESULTS Sinus rhythm was attained in 33 (76%) patients after EC (15 patients in group 1, 18 patients in group 2). No clinical signs testified on thromboembolic event were observed in patients usho underwent EC. Microemboli were not recorded by TCD, performed before and after EC, in patients of both groups.
CONCLUSION EC is not associated with microembolism in patients anticoagulated using either long-term oral anticoagulation or heparin. Because, short-term treatment with heparin seems to be as effective as long-term OA, EC could be performed early and safely.
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