Background: Direct current (DC) cardioversion is an effective method for converting atrial fibrillation (AF) to sinus rhythm. Current ESC Guidelines (1) suggest that transoesophageal echocardiography (TOE) should be performed to rule out atrial thrombi in patients undergoing DC cardioversion, unless adequate anticoagulation has been documented for 3 weeks or AF is <48 hours from a definite onset. The aim of this study was to determine the prevalence of left atrial (LA) thrombus in patients undergoing elective DC cardioversion in our center and to compare LA thrombus prevalence between the patients with different thromboembolic risks.

Patients and Methods: All patients with AF lasting >48 hours admitted to the Emergency department or Department of Cardiology at the University Hospital Centre “Sestre milosrdnice” Zagreb from January 2013 to May 2016 who underwent DC cardioversion were included in the study. Patients with AF lasting <48 hours were excluded from the study. All patients underwent preprocedural TOE to exclude LA thrombus regardless on anticoagulation status. The thromboembolic risk status was calculated for each patient using a CHA2DS2-VASc score. DC cardioversion was performed according to local protocols.

Results: Total of 139 patients were included (106/139; 76% were male) with median age of 66 years (59-72). The overall prevalence of LA thrombi was 30/139 (21.6%). 49 patients were adequately anticoagulated for at least 3 weeks prior to the peri-procedural TOE (35.2%), whereas 90 patients were inadequately anticoagulated (64.8%). 12 patients with a detected thrombus were adequately anticoagulated with warfarin (N=11) or new oral anticoagulants (N=1) out of totally 49 adequately anticoagulated patients (12/49; 24.5%). 18 patients with a detected thrombus were inadequately anticoagulated (20%) (Table 1.) There was no statistical significance between prevalence of LA thrombi between adequately vs. inadequately anticoagulated patients (12 out of 49; 24.5% vs 18 out of 90, 20%, p=0.582)

Conclusion: The prevalence of LA thrombi is high, even in patients who have been adequately anticoagulated. Further research with larger number of patients is needed to determine whether all patients should undergo TEE before elective DC cardioversion.