IMPACT OF ELECTRICAL CARDIOVERSION FOR ATRIAL-FIBRILLATION ON LEFT ATRIAL APPENDAGE FUNCTION AND SPONTANEOUS ECHO CONTRAST - CHARACTERIZATION BY SIMULTANEOUS TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Objectives. This study assessed the function of the left atrial append age in the pericardioversion period to gain insights into mechanisms i nvolved in thromboembolism after cardioversion of atrial fibrillation. Background. Systemic embolization associated with electrical cardiove rsion of atrial fibrillation is thought to originate from the left atr ium or left atrial appendage, or both. However, the mechanism involved is poorly understood. Methods. We studied left atrial appendage funct ion with transesophageal echocardiography in 20 patients with atrial f ibrillation before and after successful electrical cardioversion. We m easured left atrial appendage emptying and filling velocities by pulse d wave Doppler echocardiography, characterized Doppler emptying patter ns, measured atrial appendage areas and assessed the presence or absen ce of spontaneous echo contrast or thrombus. Results. Organized left a trial appendage function returned in 16 (80%) of 20 patients immediate ly after cardioversion. Atrial appendage emptying velocities before ca rdioversion were greater in patients without (0.39 +/- 0.02 m/s) than in those with (0.25 +/- 0.12 m/s) spontaneous echo contrast (p = 0.045 ). Furthermore, emptying velocities before cardioversion were signific antly greater than late diastolic emptying velocities after cardiovers ion (0.31 +/- 0.15 vs. 0.14 +/- 0.12 m/s, p = 0.0001), as well as in b oth the group with (0.25 +/- 0.12 vs. 0.13 +/- 0.13 m/s, p = 0.001) an d the group without (0.39 +/- 0.02 vs. 0.15 +/- 0.12 m/s, p = 0.01) sp ontaneous echo contrast. In addition, left atrial and atrial appendage spontaneous echo contrast developed in 4 of 20 patients and increased in intensity in 3 of 20 patients in the immediate postcardioversion p eriod. Conclusions. Organized left atrial appendage function returns i n most patients immediately after cardioversion of atrial fibrillation . However, its function is impaired compared with that before cardiove rsion. Furthermore, spontaneous echo contrast increased in 7 (35%) of 20 patients after cardioversion. These observations suggest that stunn ed left atrial appendage function after cardioversion may predispose t he chamber to thrombus formation, which may play a role in the mechani sm involved in the occurrence of embolization after cardioversion.