Document Detail

Left atrial appendage "stunning" after electrical cardioversion of atrial flutter: an attenuated response compared with atrial fibrillation as the mechanism for lower susceptibility to thromboembolic events.
MedLine Citation:
PMID:  9060897     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: This study sought to determine whether left atrial appendage stunning occurs in patients with atrial flutter and to compare left atrial appendage function in the pericardioversion period with that in patients with atrial fibrillation. BACKGROUND: Left atrial appendage stunning has recently been proposed as a key mechanistic phenomenon in the etiology of postcardioversion thromboembolic events in atrial fibrillation. Atrial flutter is thought to be associated with a negligible risk of thromboembolic events; therefore, anticoagulation is commonly withheld before and after cardioversion in these patients. METHODS: Sixty-three patients with atrial flutter (n = 19) or atrial fibrillation (n = 44) underwent transesophageal echocardiography immediately before and after electrical cardioversion. In addition to assessing the presence of thrombus and spontaneous echo contrast, we measured left atrial appendage emptying velocity and calculated shear rates by pulsed wave Doppler and two-dimensional echocardiography. RESULTS: Patients with atrial flutter exhibited greater left atrial appendage flow velocities before cardioversion than those with atrial fibrillation (42 +/- 19 vs. 28 +/- 15 cm/s [mean +/- SD], p < 0.001). Left atrial appendage shear rates were also higher in patients with atrial flutter (103 +/- 82 vs. 59 +/- 37 s-1, p < 0.001). After cardioversion, left atrial appendage flow velocities decreased compared with precardioversion values in patients with atrial fibrillation (28 +/- 15 before to 15 +/- 14 cm/s after cardioversion, p < 0.001) and atrial flutter (42 +/- 19 to 27 +/- 18 cm/s, respectively, p < 0.001). Shear rates decreased from 59 +/- 37 before cardioversion to 30 +/- 31 s-1 after cardioversion in atrial fibrillation (p < 0.001), and from 103 +/- 82 s to 65 +/- 52 s-1, respectively (p < 0.001), in atrial flutter. This decrease in flow velocity from before to after cardioversion occurred in 36 (82%) of 44 patients with atrial fibrillation and 14 (74%) of 19 with atrial flutter. The impaired left atrial appendage function after cardioversion was less pronounced in the group with atrial flutter (27 +/- 18 cm/s for atrial flutter vs. 15 +/- 14 cm/s for atrial fibrillation, p < 0.001). New or increased spontaneous echo contrast occurred in 22 (50%) of 44 patients with atrial fibrillation versus 4 (21%) of 19 with atrial flutter (p < 0.05). CONCLUSIONS: Left atrial appendage stunning also occurs in patients with atrial flutter, although to a lesser degree than in those with atrial fibrillation. These data suggest that patients with atrial flutter are at risk for thromboembolic events after cardioversion, although this risk is most likely lower than that in patients with atrial fibrillation because of better preserved left atrial appendage function.
R A Grimm; W J Stewart; K Arheart; J D Thomas; A L Klein
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  29     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1997 Mar 
Date Detail:
Created Date:  1997-04-04     Completed Date:  1997-04-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  582-9     Citation Subset:  AIM; IM    
Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195-5064, USA.
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MeSH Terms
Atrial Fibrillation / complications,  physiopathology,  therapy*,  ultrasonography
Atrial Flutter / complications,  physiopathology,  therapy*,  ultrasonography
Atrial Function, Left
Coronary Thrombosis / etiology,  physiopathology
Echocardiography, Doppler
Echocardiography, Transesophageal
Electric Countershock* / adverse effects
Middle Aged

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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