Impact of electrical cardioversion for atrial fibrillation on left atrial appendage function and spontaneous echo contrast: characterization by simultaneous transesophageal echocardiography.
OBJECTIVE
This study assessed the function of the left atrial appendage in the pericardioversion period to gain insights into mechanisms involved in thromboembolism after cardioversion of atrial fibrillation.


BACKGROUND
Systemic embolization associated with electrical cardioversion of atrial fibrillation is thought to originate from the left atrium or left atrial appendage, or both. However, the mechanism involved is poorly understood.


METHODS
We studied left atrial appendage function with transesophageal echocardiography in 20 patients with atrial fibrillation before and after successful electrical cardioversion. We measured left atrial appendage emptying and filling velocities by pulsed wave Doppler echocardiography, characterized Doppler emptying patterns, measured atrial appendage areas and assessed the presence or absence of spontaneous echo contrast or thrombus.


RESULTS
Organized left atrial appendage function returned in 16 (80%) of 20 patients immediately after cardioversion. Atrial appendage emptying velocities before cardioversion 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 significantly greater than late diastolic emptying velocities after cardioversion (0.31 +/- 0.15 vs. 0.14 +/- 0.12 m/s, p = 0.0001), as well as in both the group with (0.25 +/- 0.12 vs. 0.13 +/- 0.13 m/s, p = 0.001) and the group without (0.39 +/- 0.02 vs. 0.15 +/- 0.12 m/s, p = 0.01) spontaneous 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 period.


CONCLUSIONS
Organized left atrial appendage function returns in most patients immediately after cardioversion of atrial fibrillation. However, its function is impaired compared with that before cardioversion. Furthermore, spontaneous echo contrast increased in 7 (35%) of 20 patients after cardioversion. These observations suggest that stunned left atrial appendage function after cardioversion may predispose the chamber to thrombus formation, which may play a role in the mechanism involved in the occurrence of embolization after cardioversion.
Grimm
R A
RA
Department of Cardiology, Cleveland Clinic Foundation, Ohio 4195-5064.
Stewart
W J
WJ
Maloney
J D
JD
Cohen
G I
GI
Pearce
G L
GL
Salcedo
E E
EE
Klein
A L
AL
D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D016279:Atrial Function, Left; D015984:Causality; D003971:Diastole; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D004554:Electric Countershock / Q000009:adverse effects*; D005069:Evaluation Studies as Topic; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017682:Myocardial Stunning / Q000453:epidemiology / Q000209:etiology; D015588:Observer Variation; D013923:Thromboembolism / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D016277:Ventricular Function, Left